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.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.InputMismatchException;
import java.io.IOException;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main {
        public static void main(String[] args) {
                InputStream inputStream = System.in;
                OutputStream outputStream = System.out;
                InputReader in = new InputReader(inputStream);
                PrintWriter out = new PrintWriter(outputStream);
                TaskD solver = new TaskD();
                solver.solve(1, in, out);
                out.close();
        }

        static class TaskD {
                public void solve(int testNumber, InputReader in, PrintWriter out) {
                        int n = in.i();
                        long ans = 0;
                        for (int i = 4; i <= n; i++) {
                                ans += findValue(i);
                        }
                        out.println(ans * 4);
                }

                private long findValue(int n) {
                        long ans = 0;
                        for (int i = 2; i * i <= n; i++) {
                                if (n % i == 0) {
                                        if (i * i == n) {
                                                ans += n / i;
                                        } else {
                                                ans += n / i;
                                                ans += i;
                                        }
                                }
                        }
                        return ans;
                }

        }

        static class InputReader {
                InputStream is;
                private byte[] inbuf = new byte[1024];
                public int lenbuf = 0;
                public int ptrbuf = 0;

                public InputReader(InputStream is) {
                        this.is = is;
                }

                private int readByte() {
                        if (lenbuf == -1) throw new InputMismatchException();
                        if (ptrbuf >= lenbuf) {
                                ptrbuf = 0;
                                try {
                                        lenbuf = is.read(inbuf);
                                } catch (IOException e) {
                                        throw new InputMismatchException();
                                }
                                if (lenbuf <= 0) return -1;
                        }
                        return inbuf[ptrbuf++];
                }

                public int i() {
                        int num = 0, b;
                        boolean minus = false;
                        while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-')) ;
                        if (b == '-') {
                                minus = true;
                                b = readByte();
                        }

                        while (true) {
                                if (b >= '0' && b <= '9') {
                                        num = num * 10 + (b - '0');
                                } else {
                                        return minus ? -num : num;
                                }
                                b = readByte();
                        }
                }

        }
}

