Devise a recursive algorithm to find , where a is a real number and n is a positive integer. [Hint: Use the equality .]

Please help and explain the steps. Thank you.

P.S the algorithm has to should look similar to this example:

procedure square(n: nonnegative integer) if n = 0 then return 0 else return square (n ? 1) + 2(n ? 1) + 1

2n