#include <bits/stdc++.h>
using namespace std;
int div_[50001000];
int cnt[50001000];
int main(void){
    int n;
    cin >> n;
    for(int i = 1; i <= n; i++) div_[i] = 1;
    for(int j = 2; j * j <= n; j++){
        for(int k = j * j; k <= n; k += j * j){
            div_[k] = j * j;
        }
    }

    long long ans = 0;
    for(int i = 1; i <= n; i++){
        int j = i;
        if (div_[i] != 1){
            j /= div_[i];
        }
        div_[i] = j;
        cnt[j]++;
    }
    for(auto c: cnt){
        ans += (long long) c * (long long) c;
    }
    cout << ans << "\n";
}