#include <iostream>
#include <fstream>
using namespace std;

int main()
{
    ifstream input("fractii.in");
    ofstream output("fractii.out");
    int n = 0;
    input >> n;

    int sieve[n+1];

    for (int i = 0; i <= n+1; i++) {
        sieve[i] = 1;
    }

    for (int i = 2; i <= n; i++) {
        for (int j = 2; j * i <= n; j++) {
            sieve[j*i] = 0;
        }
    }

    int primes[n+1], primeCount = 0;
    for (int i = 2; i <= n; i++) {
        if (sieve[i] == 1) {
            primes[primeCount++] = i;
        }
    }

    long long phi[n+1];

    for (int i = 2; i <= n; i++) {
        phi[i] = i;
        for (int j = 0; primes[j] <= n && j < primeCount; j++) {
            if (i % primes[j] == 0) {
                phi[i] = phi[i] * (primes[j] - 1) / primes[j];
            }
        }
    }

    long long sum = 0;
    for (int i = 2; i <= n; i++) {
        sum += phi[i];
    }

    cout << sum * 2 + 1 << endl;

    output << sum * 2 + 1 << endl;

    return 0;
}