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
#include <bits/stdc++.h>
using namespace std;
long long dp[1000010];
bool not_prime[1000010];
int prime[1000010], primei = 0;
void work(int upp) {
  not_prime[1] = 1;
  for (int i = 2; i <= upp; i++) {
    if (!not_prime[i]) prime[++primei] = i;
    for (int j = 1; j <= primei && prime[j] * i <= upp; j++) {
      not_prime[prime[j] * i] = 1;
      if (i % prime[j] == 0) {
        break;
      }
    }
  }
}
int main() {
  int N;
  cin >> N;
  dp[2] = dp[3] = 0;
  work(N);
  for (int i = 4; i <= N; i++) {
    for (int j = 1; prime[j] < i && j <= primei; j++) {
      if (i % prime[j] == 0) {
        dp[i] += (long long)4 * i / prime[j];
      }
    }
    dp[i] += dp[i - 1];
  }
  cout << dp[N] << endl;
  return 0;
}
