Summing the N series

There is a sequence whose  term is

Tn = n*n-(n-1)*(n-1)

Evaluate the series

Sn = T1+T2+T3+.....+Tn

Find .

Explanation:

On solving the Tn we get Tn = 2*n-1

The Sum of the series will be n*n.

Example:

Input:  n = 2
Output: 4

Approach

C++

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

#define mod 1000000007

int summingSeries(long n)
{
    n = n % mod;
    return (n * n) % mod;
}

int main()
{

    long n = 2;

    cout << summingSeries(n) << "\n";
    return 0;
}