http://mathlesstraveled.com/2011/06/04/the-collatz-conjecture-is-safe-for-now/ http://mathlesstraveled.com/2011/06/04/the-collatz-conjectur... (At the end of t

http://mathlesstraveled.com/2011/06/04/the-collatz-conjecture-is-safe-for-now/ http://mathlesstraveled.com/2011/06/04/the-collatz-conjectur... (At the end of the comments you'll see that the author of the proof withdrew the claim.)