Each level in the pyramid is a square, so if there are n levels, the bottom level has n * n balls, and the total number of balls is just

(n * n) + (number of balls in a pyramid of height n - 1).

There is just one ball in a pyramid of height 1. Write a static recursive method getPyramidCount that takes a single int argument representing the number of levels in a pyramid, and returns the total number of balls.