#include <bits/stdc++.h>
using namespace std;
int main () {
	long long n;
	cin >> n;
	long long ans = 0;
	for (long long i = 1; i <= n - 1; ++i) {
		for (long long j = i + 1; j <= n; ++j) {
			ans += __gcd(i, j);
		}
	}
	cout << ans;
}