Hello to everyone,

I want to solve the following exercise:

Determine in how many ways can a 3xN rectangle be completely tiled with 2x1 dominoes.

From what I have found, so far, if N is odd, the answer is 0. On the other hand, if n is even, we have to find a recurrence relation that will give us the answer.

I have come accross this answer, but I cannot understand the way of thinking. For example, why do we have to declare a g function that denotes the tilings with one of its corner squares removed?

Thanks a lot,