Sum square difference(Hacker Rank)

#include<iostream>

#include<vector>

#include <algorithm>

#include<math.h>

using namespace std;

int main()

{

    int t;

    cin >> t;

    for(int a0 = 0; a0 < t; a0++)

    {

        int n;

        cin >> n;

        unsigned long long int sum = (n*(n+1))/2 * (n*(n+1))/2 ;

        unsigned long long int sum1=0;

        for(unsigned long long int j=1; j<=n; j++)

        {

            sum1  +=  j*j;

        }

        cout<<sum-sum1<<endl;

    }

    return 0;

}