Given a Rubik's Cube with a side length of n, return the number of individual stickers that are needed to cover the whole cube.

1 has 6 stickers.2 has 24 stickers.3 has 54 stickers.HowManyStickers(1) ➞ 6
HowManyStickers(2) ➞ 24
HowManyStickers(3) ➞ 54