while True:
    user_input = input("How many squares (or press Enter to quit)? ")
    if user_input == "":
        break

    n = int(user_input)
    squares = []
    
    for i in range(n+1):
        squares += [i * i]
    
    sum_of_squares = sum(squares)

    print("The sum of the first", n, "squares is:", sum_of_squares)