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


const int NMAX = 1e6;

int mobius[NMAX + 1];
int main()
{
    ifstream cin("fractii.in");
    ofstream cout("fractii.out");
    int i, n;
    cin >> n;
    mobius[1] = 1;
    for (i = 2; i <= n; i++)
    {
        mobius[i]--;
        for (int j = 2 * i; j <= n; j += i)
            mobius[j] -= mobius[i];
    }
    long long ans = 0;
    for (i = 1; i <= n; i++)
        ans += 1LL * mobius[i] * (n / i) * (n / i);
    cout << ans;
}