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;
template <class TH>
void _dbg(const char *sdbg, TH h) {
  cerr << sdbg << "=" << h << "\n";
}
template <class TH, class... TA>
void _dbg(const char *sdbg, TH h, TA... a) {
  while (*sdbg != ',') cerr << *sdbg++;
  cerr << "=" << h << ",";
  _dbg(sdbg + 1, a...);
}
const long long inf = 1000 * 1000 * 1000 + 7;
const long long INF = inf * inf;
const long long MOD = inf;
const long long N = 1e5 + 10, base = 1 << 18;
long long dp[N];
long long pierwsza[N];
long long n;
void sito() {
  pierwsza[1] = 1;
  for (long long i = 2; i < N; i++) {
    if (!pierwsza[i]) {
      pierwsza[i] = i;
      for (long long j = i * i; j < N; j += i)
        if (!pierwsza[j]) pierwsza[j] = i;
    }
  }
}
void solve() {
  cin >> n;
  for (long long i = (2); i <= (n); i++) {
    if (pierwsza[i] == i) {
      for (long long j = 2; i * j <= n; j++) dp[i] += 4 * j;
    }
  }
  long long res = 0;
  for (long long i = (2); i <= (n / 2); i++) {
    if (pierwsza[i]) res += dp[i];
  }
  cout << res << "\n";
}
int32_t main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cerr.tie(0);
  cout << setprecision(9) << fixed;
  cerr << setprecision(6) << fixed;
  sito();
  long long test = 1;
  while (test--) {
    solve();
  }
}
