[math-fun] A (non-)proof of the Collatz 3n+1 problem.

Dear funsters, Georg Fischer has an attempt of a proof for the Collatz 3n+1 problem online here: http://www.teherba.org/index.php/OEIS/3x%2B1_Problem He suspects that it contains a flaw, hence refrains from contacting any big-wigs. With his permission I'd like to ask on this list what the problem may be. Any takers? Georg will certainly add the reason for the invalidity of his proof as soon as someone points it out. Best regards, jj