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

bool e[1000001];
int a[100001];
int k;

void Ciur() {
    int i, j;
    e[1] = 1;
    for (i = 2; i * i <= 1000000; i++)
        if (e[i] == 0)
            for (j = 2; j * i <= 1000000; j++)
                e[i * j] = 1;
    for (i = 2; i <= 1000000; i++)
        if (!e[i])
            a[++k] = i;
}

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