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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#include <bits/stdc++.h>
using namespace std;
const long long mod = 1e9 + 7;
const double eps = 1e-7;
const int inf = 0x3f3f3f3f;
const int mif = 0xcfcfcfcf;
const double PI = 3.14159265358979323846264338;
long long mul_mod(long long first, long long second) {
  long long t = 0;
  while (second) {
    if (second & 1) t = (t + first) % mod;
    first = (first + first) % mod;
    second >>= 1;
  }
  return t;
}
long long pow_mod(long long first, long long second) {
  long long t = 1;
  while (second) {
    if (second & 1) t = mul_mod(t, first);
    first = mul_mod(first, first);
    second >>= 1;
  }
  return t;
}
long long quick_pow(long long first, long long second) {
  long long t;
  for (t = 1; second; second >>= 1, first *= first)
    if (second & 1) t *= first;
  return t;
}
long long gcd(long long first, long long second) {
  return second ? gcd(second, first % second) : first;
}
double LG(double s, double k) { return log(k) / log(s); }
long long read() {
  long long c = 0, f = 1ll;
  char ch = getchar();
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    c = c * 10 + ch - '0';
    ch = getchar();
  }
  return c * f;
}
const int N = 100005;
int n;
long long sum;
int main() {
  n = read();
  for (int i = 2; 2 * i <= n; ++i) sum += 2 * (2 + n / i) * (n / i - 1);
  printf("%lld\n", sum);
}
