Web Directory

» An Image from the Collatz Problem
   By Andrew Shapira. The intensity of a point denotes the time taken to terminate.
   http://www.onezero.org/collatz-image

» Collatz 3n+1 Problem Structure
   Observations posted by Ken Conrow to stimulate further research.
   http://www-personal.ksu.edu/~kconrow/

» Collatz Problem
   From Eric Weissten's World of Mathematics. Article with references and links.
   http://mathworld.wolfram.com/CollatzProblem.html

» Computational Verification of the 3x+1 Conjecture
   Results up to 2^60 by Tomás Oliveira e Silva.
   http://www.ieeta.pt/~tos/3x+1.html

» Experiments with the 3n+1 Sequence
   An online calculator by Alfred Wassermann.
   http://did.mat.uni-bayreuth.de/personen/wassermann/fun/3np1_e.html

» The 3x + 1 Problem and its Generalizations
   An activated-text survey article by Jeff Lagarias.
   http://oldweb.cecm.sfu.ca/organics/papers/lagarias/

» The 3x+1 Problem Annotated Bibliography
   By Jeffrey Lagarias, 1997.
   http://www.math.lsa.umich.edu/~lagarias/3x+1.html

» The 3x+1 Problem Conference Proceedings
   Katholische Universität Eichstätt, Germany; 5--6 August 1999. On-line proceedings and group photo.
   http://www.math.grin.edu/~chamberl/conf.html

» The Collatz 3n+1 Conjecture is Unprovable
   A paper by Craig Alan Feinstein arguing that the Collatz Conjecture cannot be formally proved.
   http://arxiv.org/abs/math.GM/0312309

» The Generalised 3x+1 Problem
   A survey by Keith Matthews.
   http://www.numbertheory.org/pdfs/survey.pdf

» The Structure of the 3x + 1 Function
   Papers by Peter Schorer describing several new approaches.
   http://www.occampress.com