#include <iostream>
#include<fstream>
#define Nmax 1000001
using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");
int sol[Nmax];
int main()
{
    int N;
    f>>N;
    for(int i=2;i<=N;i++)
        sol[i]=i-1;
    for(int i=2;i<=N;i++)
        for(int j=2*i;j<=N;j+=i)
        sol[j]-=sol[i];

long long rez=0;
for(int i=2;i<=N;i++)
    rez+=sol[i];
rez*=2;rez+=1;
cout<<rez;
    return 0;
}