#include <iostream>#include <algorithm>#include <cstdio>#include <cmath>using namespace std;const int Max=1000010;int phi[Max];int main(){	for(int i=1;i<Max;i++) phi[i]=i;	for(int i=2;i<Max;i+=2) phi[i]/=2;	for(int i=3;i<Max;i+=2){		if(phi[i]==i){			for(int j=i;j<Max;j+=i)			phi[j]=phi[j]/i*(i-1);		}	}	int n;	while(scanf("%d",&n),n){		long long ans=0;		for(int i=2;i<=n;i++)		ans+=(long long)phi[i];		printf("%lld\n",ans);	}	return 0;}