#include <iostream>
#include <fstream>
#include <stdlib.h>
#define MAX 100
using namespace std;

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

int sir(int N)
{   int *phi=(int *)malloc(1000005);
    long long sum = 0;
    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(int i = 1; i <= N; ++i)
    sum += phi[i];

    g<<(sum*2+1);

    return 0;
}

int main()
{
    int n;
    f>>n;
    sir(n);
    return 0;
}