Um, no. Collatz's conjecture was that the sequence will always reach one, and that conjecture was entirely avoided in GEB. Any number that would result in the 1-4-2-1 closed loop was referred to as "a wondrous number" in the GEB dialogs, and the concentration was on the idea that while you could test any number for the property of wondrousness, nobody knew how to prove that any given number would be wondrous without testing it. It was used as a soft introduction to the halting problem.