Determine whether the following are either a sequence or a sequence defined by a recurrence relation, or indicate what is wrong with the definition. an = 5an-1 + an-2 for every integer n _ 2 with a1 = 0. an = 6n + 2 for every positive integer n. 1, 4, 9, 16, . .., n2, ... an = an-1 + 2" + 4 for every integer n 2 2 with a1 = 1