Collatz conjecture, also known as The Syracuse Problem, the 3n + 1 conjecture or the Hailstone sequence conjecture was first described by mathematician Lothar Collatz. This conjecture is strikingly simple to formulate and incredibly hard to prove or refute. It states the following: let n be a natural number greater than 1. If n is even then divide it by 2. If n is odd, then multiply it by 3 and add 1 to the product. Repeat this process, then the resulting number sequence always converges to cycle 4,2,1.