The story
Named after Lothar Collatz, who first proposed it in 1937.
Etymology from Wiktionary, CC BY-SA 4.0.
Collatz conjecture
Today it means: The conjecture that the process of taking a number n and, if n is even, dividing it by 2, or if n is odd, multiplying it by 3 and adding 1, then repeating this process, will eventually yield 1. Full definition →