> I think it's probably pretty easy to prove that 4-2-1 is the only loop that is possible. Conjecture 2: https://terrytao.wordpress.com/2011/08/25/the-collatz-

> I think it's probably pretty easy to prove that 4-2-1 is the only loop that is possible. Conjecture 2: https://terrytao.wordpress.com/2011/08/25/the-collatz-conjecture-littlewood-offord-theory-and-powers-of-2-and-3/ https://terrytao.wordpress.com/2011/08/25/the-collatz-conjec... turns out its not :p