#include <bits/stdc++.h>

using namespace std;
ifstream in("fractii.in");
ofstream out("fractii.out");
int main(){
    int n;
    in>>n;
    vector<int> phi(n+1);
    for(int i=2;i<=n;i++){
            phi[i]+=i-1;
            for(int j=2*i;j<=n;j+=i){
                phi[j]-=phi[i];
            }
    }
    int64_t sum=0;
    for(auto i:phi)sum+=i;
    sum*=2;
    out<<sum+1;
}