1 #include<stdio.h>

 2 #include<algorithm>

 3 #include<iostream>

 4 #include<queue>

 5 #include<math.h>

 6 #include<vector>

 7 #include<bitset>

 8 using namespace std;

 9 typedef long long LL;

10 bool prime[5000000];

11 int ans[1000000];

12 int oula[5000000];

13 int main(void)

14 {

15     int i,j;

16     for(i = 0; i < 5000000; i++)

17     {

18         oula[i] = i;

19     }

20     for(i = 2; i <10000 ; i++)

21     {

22         if(!prime[i])

23         {

24             for(j = i; (i*j) <= 5000000; j++)

25                 prime[i*j] = true;

26         }

27     }

28     int cn = 0;

29     for(i = 2 ; i <= 5000000; i++)

30         if(!prime[i])

31             ans[cn++]=i;

32     oula[0] = 0;

33     oula[1] = 1;

34     for(i = 0; i < cn; i++)

35     {

36         for(j = 1; (ans[i]*j) <= 5000000; j++)

37         {

38             oula[ans[i]*j]/=ans[i];

39             oula[ans[i]*j]*=ans[i]-1;

40         }

41     }

42     int n;

43     while(scanf("%d",&n),n!=0)

44     {   LL sum=0;

45         for(i = 2;i <=n ;i++)

46         { LL ak = (LL)(1+n/i)*(LL)(n/i)/2;

47           sum+=ak*oula[i];

48         }

49         printf("%lld\n",sum);

50     }return 0;

51 }