#include <iostream>
#include <cmath>
#include <fstream>
using namespace std;
unsigned long long fct(unsigned long long n){
 unsigned long long phi,i;
 phi=n;
 for(i=2;i<=n;i++)
  if(n%i==0){
   phi-=phi/i;
   while(n%i==0)n/=i;
  }
 return phi;
}
int main()
{
    unsigned long long n,nr=0;
    ifstream fin("fractii.in");
    fin>>n;
    ofstream fout("fractii.out");
    for(unsigned long long a=2;a<=n;a++)
    {
        nr+=fct(a);
    }
	nr*=2;
	nr++;
    fout<<nr;
    cout<<nr;
}