28237
 13190
 39914
 81367
 8554
 61106
 67448
 39004
 22308
 16054
 71468
 60501
 100
 300
 59632
 90783
 5611
 1000
 69475
 69753
 10
 5
 582
 8
 36961
 5071
 20
 53213
 92775
 28738
 100000
 92280
 37944
 9
 2627
 7
 3

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import java.io.*;
import java.math.BigInteger;
import java.util.*;
                                 
public class Main {
                             
    static Scanner in;
         
//  static StreamTokenizer in;
//  static int nextInt() throws IOException {
//      in.nextToken();
//      return (int)in.nval;    
//  }
    static Random rand = new Random();
    static long gcd(long a, long c) {
        BigInteger q = BigInteger.valueOf(a);
        BigInteger w = BigInteger.valueOf(c);
        q = q.gcd(w);
        return q.longValue();
    }
    static int[] w, d;
   
    public static void main(String args[]) throws IOException {
    	
//      in = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
        in = new Scanner(System.in);         
        PrintWriter out = new PrintWriter(System.out);
        int n = in.nextInt();
        long[] pref = new long[n];
       
        pref[0] = 0;
        pref[1] = 0;
        int a = 8;
        for(int i =2;i<n;i++) {
        	pref[i] = a + pref[i-1];
        	a+=4;
        }
//        System.out.println(pref[n-1]);
        long ans = 0;
        long max = 0;
        for(int i= 2;i<n;i++) {
        	ans+= pref[n/i];
//        	System.out.println(pref[n/i]);
//        	max = Math.max(ans, max);
        }
        System.out.println(ans);
        out.close();
    }
}
                                 
class Pair implements Comparable{
	int a;
    int b;

    public Pair() {
        this.a = 0;
        this.b = 0;
    }
    public Pair(int a, int b) {
        this.a = a;
        this.b = b;

    }
    public int compareTo(Object arg0) {
        if(Integer.compare(this.a, ((Pair) arg0).a) == 0) return Integer.compare(this.b, ((Pair) arg0).b);
            return Integer.compare(this.a, ((Pair) arg0).a);
    }
}