Project Euler 6 - Sum Square Difference

'''
The sum of the squares of the first ten natural numbers is,
1^2+2^2+...+10^2=385
The square of the sum of the first ten natural numbers is,
(1+2+...+10)^2=55^2=3025
Hence the difference between the sum of the squares of the first ten natural numbers and the square of the sum is 3025−385=2640.
Find the difference between the sum of the squares of the first one hundred natural numbers and the square of the sum.
'''

def sumOfSquares(n):
    if n != int(n) or n <=0:
        return None
    sum = 0
    for i in range(n):
        sum += (i+1) ** 2
    return sum

def squareOfSum(n):
    if n != int(n) or n <=0:
        return None
    sum = 0
    for i in range(n):
        sum += (i+1)
    return sum ** 2

# MAIN FUNCTION
N = 100
answer = squareOfSum(N) - sumOfSquares(N)
print("(1 + 2 + 3 + .... + " + str(N-1) + "+ " + str(N) + ")^2 - (1^2 + 2^2 + 3^2 + .... + " + str(N-1) + "^2 + " + str(N) + "^2) = " + str(answer))