The Collatz g(z) fractal Close-up of the g(z) fractal at z = 1 clipped from en.wikipedia.org Lothar Collatz Lothar Collatz (July 6, 1910, Arnsberg , Westphalia – September 26, 1990) was a German mathematician . In 1937 he posed the famous Collatz conjecture , which remains unsolved. at 8:50 PM Email