#include<map>
#include<set>
#include<cmath>
#include<queue>
#include<stack>
#include<vector>
#include<cstdio>
#include<cassert>
#include<iomanip>
#include<cstdlib>
#include<cstring>
#include<iostream>
#include<algorithm>
#define C 0.5772156649
#define pi acos(-1.0)
#define ll long long
#define mod 1000000007
#define ls l,m,rt<<1
#define rs m+1,r,rt<<1|1
#pragma comment(linker, "/STACK:1024000000,1024000000")

using namespace std;

const double g=10.0,eps=1e-12;
const int N=1000000+10,maxn=500+100,inf=0x3f3f3f;

ll euler[N];
void geteuler()
{
    memset(euler,0,sizeof euler);
    euler[1]=1;
    for(int i=2;i<N;i++)
    {
        if(!euler[i])
        {
            for(int j=i;j<N;j+=i)
            {
                if(!euler[j])euler[j]=j;
                euler[j]=euler[j]/i*(i-1);
            }
        }
    }
}
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    geteuler();
    ll n;
    while(cin>>n,n){
        ll ans=0;
        for(ll i=2;i<=n;i++)
           ans+=euler[i];
        cout<<ans<<endl;
    }
    return 0;
}
/*********************

*********************/