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

int main() {
    int n, i, d, ci, r;
    long long rez = 0;
    ifstream f("fractii.in");
    f >> n;
    f.close();
    rez = 0;
    for (i = 2; i <= n; i++) {
        d = 2, ci = i, r = i;
        while (ci != 1) {
            if (ci % d == 0) {
                r = r / d * (d - 1);
                while (ci % d == 0) 
                    ci /= d;
            }
            d++;
            if (d * d > ci)
                d = ci;
        }
        rez += r;
    }
    ofstream g("fractii.out");
    g << 2 * rez + 1;
    g.close();
    return 0;
}