- “Deceptive puzzle may be solved after 74 years” by Jacob Aron (New Scientist; 2011.06.03) – http://www.newscientist.com/blogs/shortsharpscience/2011/06/simple-number-puzzle-possibly.html
- The Collatz conjecture was proposed by Lothar Collatz in 1937. It is also known as the “3n + 1 problem” because of its deceptively-simple definition.
- Now mathematician Gerhard Opfer [http://www.math.uni-hamburg.de/home/opfer/] of the University of Hamburg, who was a student of Collatz [http://genealogy.math.ndsu.nodak.edu/id.php?id=27958], says he has proved the conjecture true.
- Paper: “An analytic approach to the Collatz 3n + 1 problem” – http://preprint.math.uni-hamburg.de/public/papers/hbam/hbam2011-09.pdf