In the questions below give a recursive definition with initial condition(s) of the set.S 15. 3,7,11,15,19,23... 17. Find/(2) and (3) iff(n)-(-I) (n-2)+1, 0)-1, (1)-4 18. Suppose (a, is defined recursively by , -1 and that a, 2 Find a, and a.. 19. Describe a recursive algorithm for computing 3o where n is a nonnegative integer