#include <bits/stdc++.h>
typedef long long int ll;
using namespace std;
int main()
{
   ll n;
   while(cin >> n and n)
   {
       ll res = 0, p = 0 ,a;
       ll k = 1;
       for(int i = 1; i <= n; i++)
       {
             if(k >= n)
            break;
           a = n / k , p = n / a;
           res += a * ((k + p) * (p -k + 1)/ 2);
          k = p + 1;

       }

       cout<< res  - 1<< endl;
   }


}