An arithmetic sequence is a sequence of numbers such that the difference between the consecutive terms is constant.
The recursive formula have the following format:

Where 'd' is the common difference between each term.
From the text, we know that

Plugging those values in our formula, we find that the common difference between our terms is 3.
This gives us the following recursive function:

Evaluating the function at '5' and '6', we get the following:
