## Collatz Proof Proposed: Hailstone Sequences End In 1 90

mikejuk writes

*"A proof [preprint PDF] has been proposed for the Collatz conjecture about hailstone sequences. A hailstone sequence starts from any positive integer n the next number in the sequence is n/2 if n is even and 3n+1 if n is odd. The conjecture is that this simple sequence always ends in one. Simple to state but very difficult to prove and it has taken more than 60 years to get close to a solution."*
## before too many question this (Score:4, Informative)

The sequence ends in 1 rather than 1, 4, 2, 1, 4, 2..... by definition. A hailstone sequence has one additional rule, which is that the first 1 is the last 1, and the sequence ends.