2. Recursive Definitions (12 points) (1) (4 points) Write down the first 6 elements of the following sequence (where n Z+), then give a recursive definition for an Do not forget the base case. (You do not need to prove it is correct) a) a3n -10 (c) an 2n (2) (4 points) Give a recursive algorithm to compute the length of an array of positive integers A. You can assume that the final element of the array is a -1. Also give the initial call to your recursive algorithm. (3) (4 points) Define A as follows: 1 0 Prove the following using weak induction: n+1 n fn fn-I