import java.io.*;
import java.util.*;

class Main {
    public static void main(String[] args) throws IOException {
        Scan sc= new Scan();
        int n = sc.scanInt()+1;
        int k = sc.scanInt();
        double[] dp = new double[n];
        Arrays.fill(dp, Integer.MAX_VALUE);
        double res = 0;
        double prob = 1.0/(n-1);
        for(int i = n-1; i >= 1; --i){
            if(i >= k){
                dp[i] = 1.0;    
            }
            else {
                int steps = 2;
                int j= i*2;
                while(true){
                    if(j < n && dp[j] < Integer.MAX_VALUE){
                        break;
                    }
                    steps <<= 1;
                    j*=2;
                    if(j >= k)
                        break;
                }
                dp[i] = (j < n? dp[j] : 1) *steps;
            }
            res += prob*(1.0/dp[i]);
        }
        
        System.out.println(res);
        
    }
}

class Scan
{
    private byte[] buf=new byte[1024];
    private int index;
    private InputStream in;
    private int total;
    public Scan()
    {
        in=System.in;
    }
    public int scan()throws IOException
    {
        if(total<0)
        throw new InputMismatchException();
        if(index>=total)
        {
            index=0;
            total=in.read(buf);
            if(total<=0)
            return -1;
        }
        return buf[index++];
    }
    public int scanInt()throws IOException
    {
        int integer=0;
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        int neg=1;
        if(n=='-')
        {
            neg=-1;
            n=scan();
        }
        while(!isWhiteSpace(n))
        {
            if(n>='0'&&n<='9')
            {
                integer*=10;
                integer+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        }
        return neg*integer;
    }
    public double scanDouble()throws IOException
    {
        double doub=0;
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        int neg=1;
        if(n=='-')
        {
            neg=-1;
            n=scan();
        }
        while(!isWhiteSpace(n)&&n!='.')
        {
            if(n>='0'&&n<='9')
            {
                doub*=10;
                doub+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        }
        if(n=='.')
        {
            n=scan();
            double temp=1;
            while(!isWhiteSpace(n))
            {
                if(n>='0'&&n<='9')
                {
                    temp/=10;
                    doub+=(n-'0')*temp;
                    n=scan();
                }
                else throw new InputMismatchException();
            }
        }
        return doub*neg;
    }
    public String scanString()throws IOException
    {
        StringBuilder sb=new StringBuilder();
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        while(!isWhiteSpace(n))
        {
            sb.append((char)n);
            n=scan();
        }
        return sb.toString();
    }
    private boolean isWhiteSpace(int n)
    {
        if(n==' '||n=='\n'||n=='\r'||n=='\t'||n==-1)
        return true;
        return false;
    }
} import java.io.*; io.* java import java.util.*; util.* java class Main {
    public static void main(String[] args) throws IOException {
        Scan sc= new Scan();
        int n = sc.scanInt()+1;
        int k = sc.scanInt();
        double[] dp = new double[n];
        Arrays.fill(dp, Integer.MAX_VALUE);
        double res = 0;
        double prob = 1.0/(n-1);
        for(int i = n-1; i >= 1; --i){
            if(i >= k){
                dp[i] = 1.0;    
            }
            else {
                int steps = 2;
                int j= i*2;
                while(true){
                    if(j < n && dp[j] < Integer.MAX_VALUE){
                        break;
                    }
                    steps <<= 1;
                    j*=2;
                    if(j >= k)
                        break;
                }
                dp[i] = (j < n? dp[j] : 1) *steps;
            }
            res += prob*(1.0/dp[i]);
        }
        
        System.out.println(res);
        
    }
} Main public static void main(String[] args) throws IOException {
        Scan sc= new Scan();
        int n = sc.scanInt()+1;
        int k = sc.scanInt();
        double[] dp = new double[n];
        Arrays.fill(dp, Integer.MAX_VALUE);
        double res = 0;
        double prob = 1.0/(n-1);
        for(int i = n-1; i >= 1; --i){
            if(i >= k){
                dp[i] = 1.0;    
            }
            else {
                int steps = 2;
                int j= i*2;
                while(true){
                    if(j < n && dp[j] < Integer.MAX_VALUE){
                        break;
                    }
                    steps <<= 1;
                    j*=2;
                    if(j >= k)
                        break;
                }
                dp[i] = (j < n? dp[j] : 1) *steps;
            }
            res += prob*(1.0/dp[i]);
        }
        
        System.out.println(res);
        
    } main {
        Scan sc= new Scan();
        int n = sc.scanInt()+1;
        int k = sc.scanInt();
        double[] dp = new double[n];
        Arrays.fill(dp, Integer.MAX_VALUE);
        double res = 0;
        double prob = 1.0/(n-1);
        for(int i = n-1; i >= 1; --i){
            if(i >= k){
                dp[i] = 1.0;    
            }
            else {
                int steps = 2;
                int j= i*2;
                while(true){
                    if(j < n && dp[j] < Integer.MAX_VALUE){
                        break;
                    }
                    steps <<= 1;
                    j*=2;
                    if(j >= k)
                        break;
                }
                dp[i] = (j < n? dp[j] : 1) *steps;
            }
            res += prob*(1.0/dp[i]);
        }
        
        System.out.println(res);
        
    } Scan sc= new Scan(); sc new Scan() int n = sc.scanInt()+1; n sc.scanInt()+1 sc.scanInt() sc.scanInt sc 1 int k = sc.scanInt(); k sc.scanInt() sc.scanInt sc double[] dp = new double[n]; dp new double[n] n Arrays.fill(dp, Integer.MAX_VALUE) Arrays.fill Arrays dp Integer.MAX_VALUE Integer Integer.MAX_VALUE double res = 0; res 0 double prob = 1.0/(n-1); prob 1.0/(n-1) 1.0 (n-1) n 1 for(int i = n-1; i >= 1; --i){
            if(i >= k){
                dp[i] = 1.0;    
            }
            else {
                int steps = 2;
                int j= i*2;
                while(true){
                    if(j < n && dp[j] < Integer.MAX_VALUE){
                        break;
                    }
                    steps <<= 1;
                    j*=2;
                    if(j >= k)
                        break;
                }
                dp[i] = (j < n? dp[j] : 1) *steps;
            }
            res += prob*(1.0/dp[i]);
        } int i = n-1; int i = n-1; i n-1 n 1 i >= 1 i 1 --i --i i {
            if(i >= k){
                dp[i] = 1.0;    
            }
            else {
                int steps = 2;
                int j= i*2;
                while(true){
                    if(j < n && dp[j] < Integer.MAX_VALUE){
                        break;
                    }
                    steps <<= 1;
                    j*=2;
                    if(j >= k)
                        break;
                }
                dp[i] = (j < n? dp[j] : 1) *steps;
            }
            res += prob*(1.0/dp[i]);
        } {
            if(i >= k){
                dp[i] = 1.0;    
            }
            else {
                int steps = 2;
                int j= i*2;
                while(true){
                    if(j < n && dp[j] < Integer.MAX_VALUE){
                        break;
                    }
                    steps <<= 1;
                    j*=2;
                    if(j >= k)
                        break;
                }
                dp[i] = (j < n? dp[j] : 1) *steps;
            }
            res += prob*(1.0/dp[i]);
        } if(i >= k){
                dp[i] = 1.0;    
            }
            else {
                int steps = 2;
                int j= i*2;
                while(true){
                    if(j < n && dp[j] < Integer.MAX_VALUE){
                        break;
                    }
                    steps <<= 1;
                    j*=2;
                    if(j >= k)
                        break;
                }
                dp[i] = (j < n? dp[j] : 1) *steps;
            } i >= k i k {
                dp[i] = 1.0;    
            } dp[i] = 1.0 dp[i] dp i 1.0 {
                int steps = 2;
                int j= i*2;
                while(true){
                    if(j < n && dp[j] < Integer.MAX_VALUE){
                        break;
                    }
                    steps <<= 1;
                    j*=2;
                    if(j >= k)
                        break;
                }
                dp[i] = (j < n? dp[j] : 1) *steps;
            } int steps = 2; steps 2 int j= i*2; j i*2 i 2 while(true){
                    if(j < n && dp[j] < Integer.MAX_VALUE){
                        break;
                    }
                    steps <<= 1;
                    j*=2;
                    if(j >= k)
                        break;
                } true {
                    if(j < n && dp[j] < Integer.MAX_VALUE){
                        break;
                    }
                    steps <<= 1;
                    j*=2;
                    if(j >= k)
                        break;
                } if(j < n && dp[j] < Integer.MAX_VALUE){
                        break;
                    } j < n && dp[j] < Integer.MAX_VALUE j < n j n dp[j] < Integer.MAX_VALUE dp[j] dp j Integer.MAX_VALUE Integer Integer.MAX_VALUE {
                        break;
                    } break; steps <<= 1 steps 1 j*=2 j 2 if(j >= k)
                        break; j >= k j k break; dp[i] = (j < n? dp[j] : 1) *steps dp[i] dp i (j < n? dp[j] : 1) *steps (j < n? dp[j] : 1) j < n j n dp[j] dp j 1 steps res += prob*(1.0/dp[i]) res prob*(1.0/dp[i]) prob (1.0/dp[i]) 1.0 dp[i] dp i System.out.println(res) System.out.println System.out System System.out res String[] args args class Scan
{
    private byte[] buf=new byte[1024];
    private int index;
    private InputStream in;
    private int total;
    public Scan()
    {
        in=System.in;
    }
    public int scan()throws IOException
    {
        if(total<0)
        throw new InputMismatchException();
        if(index>=total)
        {
            index=0;
            total=in.read(buf);
            if(total<=0)
            return -1;
        }
        return buf[index++];
    }
    public int scanInt()throws IOException
    {
        int integer=0;
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        int neg=1;
        if(n=='-')
        {
            neg=-1;
            n=scan();
        }
        while(!isWhiteSpace(n))
        {
            if(n>='0'&&n<='9')
            {
                integer*=10;
                integer+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        }
        return neg*integer;
    }
    public double scanDouble()throws IOException
    {
        double doub=0;
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        int neg=1;
        if(n=='-')
        {
            neg=-1;
            n=scan();
        }
        while(!isWhiteSpace(n)&&n!='.')
        {
            if(n>='0'&&n<='9')
            {
                doub*=10;
                doub+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        }
        if(n=='.')
        {
            n=scan();
            double temp=1;
            while(!isWhiteSpace(n))
            {
                if(n>='0'&&n<='9')
                {
                    temp/=10;
                    doub+=(n-'0')*temp;
                    n=scan();
                }
                else throw new InputMismatchException();
            }
        }
        return doub*neg;
    }
    public String scanString()throws IOException
    {
        StringBuilder sb=new StringBuilder();
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        while(!isWhiteSpace(n))
        {
            sb.append((char)n);
            n=scan();
        }
        return sb.toString();
    }
    private boolean isWhiteSpace(int n)
    {
        if(n==' '||n=='\n'||n=='\r'||n=='\t'||n==-1)
        return true;
        return false;
    }
} Scan private byte[] buf=new byte[1024]; buf new byte[1024] 1024 private int index; index private InputStream in; in private int total; total public Scan()
    {
        in=System.in;
    } Scan {
        in=System.in;
    } in=System.in in System.in System System.in public int scan()throws IOException
    {
        if(total<0)
        throw new InputMismatchException();
        if(index>=total)
        {
            index=0;
            total=in.read(buf);
            if(total<=0)
            return -1;
        }
        return buf[index++];
    } scan {
        if(total<0)
        throw new InputMismatchException();
        if(index>=total)
        {
            index=0;
            total=in.read(buf);
            if(total<=0)
            return -1;
        }
        return buf[index++];
    } if(total<0)
        throw new InputMismatchException(); total<0 total 0 throw new InputMismatchException(); new InputMismatchException() if(index>=total)
        {
            index=0;
            total=in.read(buf);
            if(total<=0)
            return -1;
        } index>=total index total {
            index=0;
            total=in.read(buf);
            if(total<=0)
            return -1;
        } index=0 index 0 total=in.read(buf) total in.read(buf) in.read in buf if(total<=0)
            return -1; total<=0 total 0 return -1; -1 1 return buf[index++]; buf[index++] buf index++ index public int scanInt()throws IOException
    {
        int integer=0;
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        int neg=1;
        if(n=='-')
        {
            neg=-1;
            n=scan();
        }
        while(!isWhiteSpace(n))
        {
            if(n>='0'&&n<='9')
            {
                integer*=10;
                integer+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        }
        return neg*integer;
    } scanInt {
        int integer=0;
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        int neg=1;
        if(n=='-')
        {
            neg=-1;
            n=scan();
        }
        while(!isWhiteSpace(n))
        {
            if(n>='0'&&n<='9')
            {
                integer*=10;
                integer+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        }
        return neg*integer;
    } int integer=0; integer 0 int n=scan(); n scan() scan while(isWhiteSpace(n))
        n=scan(); isWhiteSpace(n) isWhiteSpace n n=scan() n scan() scan int neg=1; neg 1 if(n=='-')
        {
            neg=-1;
            n=scan();
        } n=='-' n '-' {
            neg=-1;
            n=scan();
        } neg=-1 neg -1 1 n=scan() n scan() scan while(!isWhiteSpace(n))
        {
            if(n>='0'&&n<='9')
            {
                integer*=10;
                integer+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        } !isWhiteSpace(n) isWhiteSpace(n) isWhiteSpace n {
            if(n>='0'&&n<='9')
            {
                integer*=10;
                integer+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        } if(n>='0'&&n<='9')
            {
                integer*=10;
                integer+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException(); n>='0'&&n<='9' n>='0' n '0' n<='9' n '9' {
                integer*=10;
                integer+=n-'0';
                n=scan();
            } integer*=10 integer 10 integer+=n-'0' integer n-'0' n '0' n=scan() n scan() scan throw new InputMismatchException(); new InputMismatchException() return neg*integer; neg*integer neg integer public double scanDouble()throws IOException
    {
        double doub=0;
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        int neg=1;
        if(n=='-')
        {
            neg=-1;
            n=scan();
        }
        while(!isWhiteSpace(n)&&n!='.')
        {
            if(n>='0'&&n<='9')
            {
                doub*=10;
                doub+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        }
        if(n=='.')
        {
            n=scan();
            double temp=1;
            while(!isWhiteSpace(n))
            {
                if(n>='0'&&n<='9')
                {
                    temp/=10;
                    doub+=(n-'0')*temp;
                    n=scan();
                }
                else throw new InputMismatchException();
            }
        }
        return doub*neg;
    } scanDouble {
        double doub=0;
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        int neg=1;
        if(n=='-')
        {
            neg=-1;
            n=scan();
        }
        while(!isWhiteSpace(n)&&n!='.')
        {
            if(n>='0'&&n<='9')
            {
                doub*=10;
                doub+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        }
        if(n=='.')
        {
            n=scan();
            double temp=1;
            while(!isWhiteSpace(n))
            {
                if(n>='0'&&n<='9')
                {
                    temp/=10;
                    doub+=(n-'0')*temp;
                    n=scan();
                }
                else throw new InputMismatchException();
            }
        }
        return doub*neg;
    } double doub=0; doub 0 int n=scan(); n scan() scan while(isWhiteSpace(n))
        n=scan(); isWhiteSpace(n) isWhiteSpace n n=scan() n scan() scan int neg=1; neg 1 if(n=='-')
        {
            neg=-1;
            n=scan();
        } n=='-' n '-' {
            neg=-1;
            n=scan();
        } neg=-1 neg -1 1 n=scan() n scan() scan while(!isWhiteSpace(n)&&n!='.')
        {
            if(n>='0'&&n<='9')
            {
                doub*=10;
                doub+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        } !isWhiteSpace(n)&&n!='.' !isWhiteSpace(n) isWhiteSpace(n) isWhiteSpace n n!='.' n '.' {
            if(n>='0'&&n<='9')
            {
                doub*=10;
                doub+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        } if(n>='0'&&n<='9')
            {
                doub*=10;
                doub+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException(); n>='0'&&n<='9' n>='0' n '0' n<='9' n '9' {
                doub*=10;
                doub+=n-'0';
                n=scan();
            } doub*=10 doub 10 doub+=n-'0' doub n-'0' n '0' n=scan() n scan() scan throw new InputMismatchException(); new InputMismatchException() if(n=='.')
        {
            n=scan();
            double temp=1;
            while(!isWhiteSpace(n))
            {
                if(n>='0'&&n<='9')
                {
                    temp/=10;
                    doub+=(n-'0')*temp;
                    n=scan();
                }
                else throw new InputMismatchException();
            }
        } n=='.' n '.' {
            n=scan();
            double temp=1;
            while(!isWhiteSpace(n))
            {
                if(n>='0'&&n<='9')
                {
                    temp/=10;
                    doub+=(n-'0')*temp;
                    n=scan();
                }
                else throw new InputMismatchException();
            }
        } n=scan() n scan() scan double temp=1; temp 1 while(!isWhiteSpace(n))
            {
                if(n>='0'&&n<='9')
                {
                    temp/=10;
                    doub+=(n-'0')*temp;
                    n=scan();
                }
                else throw new InputMismatchException();
            } !isWhiteSpace(n) isWhiteSpace(n) isWhiteSpace n {
                if(n>='0'&&n<='9')
                {
                    temp/=10;
                    doub+=(n-'0')*temp;
                    n=scan();
                }
                else throw new InputMismatchException();
            } if(n>='0'&&n<='9')
                {
                    temp/=10;
                    doub+=(n-'0')*temp;
                    n=scan();
                }
                else throw new InputMismatchException(); n>='0'&&n<='9' n>='0' n '0' n<='9' n '9' {
                    temp/=10;
                    doub+=(n-'0')*temp;
                    n=scan();
                } temp/=10 temp 10 doub+=(n-'0')*temp doub (n-'0')*temp (n-'0') n '0' temp n=scan() n scan() scan throw new InputMismatchException(); new InputMismatchException() return doub*neg; doub*neg doub neg public String scanString()throws IOException
    {
        StringBuilder sb=new StringBuilder();
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        while(!isWhiteSpace(n))
        {
            sb.append((char)n);
            n=scan();
        }
        return sb.toString();
    } scanString {
        StringBuilder sb=new StringBuilder();
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        while(!isWhiteSpace(n))
        {
            sb.append((char)n);
            n=scan();
        }
        return sb.toString();
    } StringBuilder sb=new StringBuilder(); sb new StringBuilder() int n=scan(); n scan() scan while(isWhiteSpace(n))
        n=scan(); isWhiteSpace(n) isWhiteSpace n n=scan() n scan() scan while(!isWhiteSpace(n))
        {
            sb.append((char)n);
            n=scan();
        } !isWhiteSpace(n) isWhiteSpace(n) isWhiteSpace n {
            sb.append((char)n);
            n=scan();
        } sb.append((char)n) sb.append sb (char)n n=scan() n scan() scan return sb.toString(); sb.toString() sb.toString sb private boolean isWhiteSpace(int n)
    {
        if(n==' '||n=='\n'||n=='\r'||n=='\t'||n==-1)
        return true;
        return false;
    } isWhiteSpace {
        if(n==' '||n=='\n'||n=='\r'||n=='\t'||n==-1)
        return true;
        return false;
    } if(n==' '||n=='\n'||n=='\r'||n=='\t'||n==-1)
        return true; n==' '||n=='\n'||n=='\r'||n=='\t'||n==-1 n=='\t' n=='\r' n==' '||n=='\n'||n=='\r'||n=='\t'||n==-1 n==' ' n ' ' n=='\n' n '\n' n=='\r' n '\r' n=='\t' n '\t' n==-1 n -1 1 return true; true return false; false int n n
import java.io.*;
import java.util.*;

class Main {
    public static void main(String[] args) throws IOException {
        Scan sc= new Scan();
        int n = sc.scanInt()+1;
        int k = sc.scanInt();
        double[] dp = new double[n];
        Arrays.fill(dp, Integer.MAX_VALUE);
        double res = 0;
        double prob = 1.0/(n-1);
        for(int i = n-1; i >= 1; --i){
            if(i >= k){
                dp[i] = 1.0;    
            }
            else {
                int steps = 2;
                int j= i*2;
                while(true){
                    if(j < n && dp[j] < Integer.MAX_VALUE){
                        break;
                    }
                    steps <<= 1;
                    j*=2;
                    if(j >= k)
                        break;
                }
                dp[i] = (j < n? dp[j] : 1) *steps;
            }
            res += prob*(1.0/dp[i]);
        }
        
        System.out.println(res);
        
    }
}

class Scan
{
    private byte[] buf=new byte[1024];
    private int index;
    private InputStream in;
    private int total;
    public Scan()
    {
        in=System.in;
    }
    public int scan()throws IOException
    {
        if(total<0)
        throw new InputMismatchException();
        if(index>=total)
        {
            index=0;
            total=in.read(buf);
            if(total<=0)
            return -1;
        }
        return buf[index++];
    }
    public int scanInt()throws IOException
    {
        int integer=0;
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        int neg=1;
        if(n=='-')
        {
            neg=-1;
            n=scan();
        }
        while(!isWhiteSpace(n))
        {
            if(n>='0'&&n<='9')
            {
                integer*=10;
                integer+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        }
        return neg*integer;
    }
    public double scanDouble()throws IOException
    {
        double doub=0;
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        int neg=1;
        if(n=='-')
        {
            neg=-1;
            n=scan();
        }
        while(!isWhiteSpace(n)&&n!='.')
        {
            if(n>='0'&&n<='9')
            {
                doub*=10;
                doub+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        }
        if(n=='.')
        {
            n=scan();
            double temp=1;
            while(!isWhiteSpace(n))
            {
                if(n>='0'&&n<='9')
                {
                    temp/=10;
                    doub+=(n-'0')*temp;
                    n=scan();
                }
                else throw new InputMismatchException();
            }
        }
        return doub*neg;
    }
    public String scanString()throws IOException
    {
        StringBuilder sb=new StringBuilder();
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        while(!isWhiteSpace(n))
        {
            sb.append((char)n);
            n=scan();
        }
        return sb.toString();
    }
    private boolean isWhiteSpace(int n)
    {
        if(n==' '||n=='\n'||n=='\r'||n=='\t'||n==-1)
        return true;
        return false;
    }
}
