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;
double gcd(double a, double b) { return a < 0.01 ? b : gcd(fmod(b, a), a); }
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long int n;
  cin >> n;
  if (n == 2 || n == 3) {
    cout << 0;
    return 0;
  }
  long long int p[n + 1];
  vector<long long int> v;
  for (long long i = 0; i < int(n); i++) p[i] = 0;
  p[n + 1] = 0;
  for (int i = 2; i <= n; i++) {
    if (!p[i]) p[i] = i, v.push_back(i);
    for (int j = 0; j < v.size() && v[j] <= p[i] && i * v[j] <= n; j++)
      p[i * v[j]] = v[j];
  }
  long long int kv = 0;
  for (int i = 4; i <= n; i++) {
    long long int x = i;
    vector<pair<long long int, long long int>> t;
    long long int c = 0, q = p[x];
    while (x > 1) {
      if (q == p[x])
        c++;
      else
        t.push_back({q, c}), c = 1, q = p[x];
      x /= p[x];
    }
    t.push_back({q, c});
    c = 1;
    for (int j = 0; j < t.size(); j++) {
      c *= (pow(t[j].first, t[j].second + 1) - 1) / (t[j].first - 1);
    }
    kv += c;
  }
  cout << (kv - (n * n + 3 * n) / 2 + 9) * 4;
  return 0;
}
