/*
	Name: Farey Sequence  pku 2478
	Copyright: Shangli Cloud
	Author: Shangli Cloud
	Date: 01/08/14 15:59
	Description: 
*/
#include"iostream"
#include"cstdio"
#include"cstring"
#include"algorithm"
using namespace std;
const int ms=1e6+1;
long long phi[ms];
void solve(int n)
{
	long long ans=0;
	for(int i=2;i<=n;i++)
		ans+=phi[i];
	cout<<ans<<endl;
	return ; 
}
int main()
{
	int i,j,p;
	for(i=1;i<ms;i++)
		phi[i]=i;
	for(i=2;i<ms;i+=2)
		phi[i]/=2;
	for(i=3;i<ms;i++)
		if(phi[i]==i)
			for(j=i;j<ms;j+=i)
				phi[j]=phi[j]/i*(i-1);
	while(cin>>p,p)
		solve(p);
	return 0;
}