#include <fstream>
#define MAX 1000001
using namespace std;

int main()
{
    ifstream f("fractii.in");
    ofstream g("fractii.out");

    unsigned long long n,s=0,i,j,phi[MAX];
    f>>n;
    f.close();

    for(i=2;i<=n;i++)
        phi[i]=i;

    for(i=2;i<=n;i++)
      if(phi[i]==i)
        for(j=i; j<=n; j+=i)
        { phi[j]/=i;
          phi[j]*=i-1;
        }

    for(i=2;i<=n;i++)
        s+=phi[i];

    s=(s<<1)+1;
    g<<s;
    g.close();
    return 0;
}