6. The product of any four consecutive natural numbers is equal to some perfect square minus 1. Two numbers are consecutive if the second number is one greater than the first number. A natural number c is a perfect square if there exists natural number y such that x = y'. For example, 3 . 4 . 5 . 6 = 360 = 316 - 1 = 19- - 1. (a) Rewrite the claim in predicate logic. (b) Prove the claim