Exercise 1 (10 point). A permutation of the set {1, 2,...,n} is a bijective function 0 : {1,2,...,n} + {1, 2,...,n}. It can also be seen as an array of length n containing the entries {1,2,...,n} (not necessarily in that order) as discussed in class. Let sn denote the no. of permutations of {1, 2, ..., n} For n > 2, find a recursive formula for Sn. Using the said recursive formula and induction prove that sn= n