Let cn be the number of binary strings of length n in which every block of consecutive os or 1s has odd length. for example, if n = 3 the allowed strings are 000, 111, 010, 101 and for n = 4 we have 0001, 1110, 0101, 1010, 0111, 1000. find (and prove) a formula for cn in terms of the fibonacci numbers fn. for the fibonacci numbers, use the indexing fi = 1, f2 = 1.