Formulate the recursive formula for the following geometric sequence.
{-16, 4, -1, }

4 / -16 = -1/4. (also -1/4 = -1/4).

The general form of the sequence is:
a, ar, ar^2, ar^3

Where r is the ratio: 1/4, and a is first term: -16.

You can see each term is just ar^n where n is the term number, starting where the first term n=0.

So the general formula would be:

-16(-1/4)^n