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

1028306548 224346172 2054738392 8539207488 94344524 4816051228 5867563092 1962150044 641839188 332342852 6587875268 4721174212 12600 115440 4586497300 10630118936 40580456 1286328 6225539588 6275533596 92 8 434692 52 1762017168 33141852 440 3652070664 11101694484 1065137992 12898363344 10983871880 1856988304 64 8885348 28 0
//package Graphs;

import java.io.PrintWriter;
import java.util.Arrays;
import java.util.Random;
import java.util.Scanner;

public class M1062D {
    public static Scanner enter = new Scanner(System.in);
    public static Random random = new Random();
    public static PrintWriter out = new PrintWriter(System.out);
    public static void main(String[] args) {
        int n=enter.nextInt();
        eratosfen pr=new eratosfen(n);
        pr.fillSieve();
        long ans=0;
        //System.out.println(Arrays.toString(pr.primes));
        for (int i = 2; i <=n ; i++) {
            if(!pr.primes[i]) continue;
            ans+=2*(2+n/i)*(n/i-1);
        }
        System.out.println(ans);

    }
}

class eratosfen {
    boolean[] primes;
    public eratosfen(int n) {
        primes=new boolean[n+1];
    }
    public void fillSieve() {
        Arrays.fill(primes, true);
        primes[0] = false;
        primes[1] = false;
        for (int i = 2; i < primes.length; ++i) {
            if (primes[i]) {
                for (int j = 2; i * j < primes.length; ++j) {
                    primes[i * j] = false;
                }
            }
        }
    }
}