#pragma GCC optimize(3)
#include <cstdio>
#include <iostream>
#include <algorithm>
#include <cstring>
#include <cmath>
using namespace std;

using LL = long long;
const int MAXN = 2e6 + 5;
LL N, ans;
LL f[MAXN], g[MAXN];

int main(){
  while(cin >> N){
    if(!N) break;
    ans = 0;
    int i, j;
    for(i = 1; i <= N; i++) f[i] = (N / i) * (N / i);
    for(i = N; i >= 1; i--){
      LL tmp = 0;
      for(j = 2 * i; j <= N; j += i) tmp += g[j];
      g[i] = f[i] - tmp;
    }
    for(i = 1; i <= N; i++) ans += i * g[i];
    ans = (ans - N * (N + 1) / 2) / 2;
    cout << ans << endl;
  }
  return 0;
}