The 3n + 1 problem is deceptively simple. Consider a function f(n) and a sequence ai where:
|f(n) =||3n+1 where n is odd|
|n/2 where n is even|
|ai =||n where i = 0|
|f(ai-1) where i > 1|
The Collatz conjecture states that ai will become 1 for some i regardless of what value of n is chosen initially. It remains to date a conjecture as there is no proof for it, but there is no counterexample either.