Shifting Series

#include <iostream>
using namespace std;
int main()
{
    int n = 0;
    cin >> n;
    int left = 1;
    int middle = 2;
    int right = 3;
    int series = 1*2;
    while (right < 2 * n) {
        left++;
        middle++;
        right++;
        series += left * middle * right;
    }
    cout << series << endl;
}