#include<iostream>
#include<fstream>
#include<cmath>

using namespace std;

ifstream fin("fractii.in");
ofstream fout("fractii.out");

long long n, i, j, num,  nr;
int *phi;

int main(){

         while ( fin>>n ){
                  nr=0;
                  phi = new int[n+1];

                  for (int i = 1; i <= n; i++)
                           phi[i] = i-1;

                  for (int i = 2; i <= n; ++i)
                           for (int j = 2*i; j <= n; j += i)
                                    phi[j] -= phi[i];

                  for( i=1; i<=n; i++)
                           nr+=phi[i];

                  fout<<2*nr+1<<'\n';

                  delete phi;
         }
return 0;
}