Base Case of the Pyramid

A recursive definition (or a recursive algorithm) needs two parts:

1. If the problem is easy, solve it immediately.
2. If the problem can't be solved immediately, divide it into smaller problems, then:
   • Solve the smaller problems by applying this procedure to each of them.

In terms of pyramidal numbers, this is:

Pyramid(1) = 1
Pyramid(N) = Pyramid(N-1) + Triangle(N)

Oddly, the base case for pyramidal numbers is the peak of the pyramid.