Problem 28 - What is the sum of both diagonals in a 1001 by 1001 spiral?

링크

Starting with the number 1 and moving to the right in a clockwise direction a 5 by 5 spiral is formed as follows:

21 22 23 24 25
20  7  8  9 10
19  6  1  2 11
18  5  4  3 12
17 16 15 14 13

It can be verified that the sum of the numbers on the diagonals is 101.

What is the sum of the numbers on the diagonals in a 1001 by 1001 spiral formed in the same way?

손으로 풀 수도 있으나 귀찮아서 파이썬 ㄱㄱ

python

sum([4*x*x - 6*x + 6 for x in range(3, 1003, 2)]) + 1