#!/bin/python3

import sys

def sumOfGroup(k):
    # Return the sum of the elements of the k'th group.
    i = 0
    sum = 0 
    met = k
    od = 1
    while i < k:
        p = met*(met-1) + od
        sum = sum + p
        i += 1 
        od = od + 2
    
    return sum
if __name__ == "__main__":
    k = int(input().strip())
    answer = sumOfGroup(k)
    print(answer)