#include<bits/stdc++.h>
using namespace::std;

const int N = 50000000 + 5;

int n;
int cnt[N];
int primos[N];
int sqfree[N];
bool composite[N];

void init(){
	int len = 0;
	sqfree[1] = 1;
	for(int i = 2; i < N; i++){
		if(not composite[i]){
			primos[len++] = i;
			sqfree[i] = i;
		}
		for(int j = 0; j < len and i * primos[j] < N; j++){
			int p = primos[j];
			composite[i * p] = true;
			if(i % p == 0){
				sqfree[i * p] = sqfree[i] % p == 0 ? sqfree[i] / p : sqfree[i] * p;
				break;
			}
			else{
				sqfree[i * primos[j]] = sqfree[i] * primos[j];
			}
		}
	}
}

int main(){
	init();
	scanf("%d", &n);
	for(int i = 1; i <= n; i++) cnt[sqfree[i]]++;
	long long ans = 0;
	for(int i = 1; i <= n; i++){
		ans += 1ll * cnt[i] * cnt[i];
	}
	printf("%lld\n", ans);
	return 0;
}