ABC Conjecture
A New Extreme ABC-example, Good ABC-Ratios, Introduction to the ABC Conjecture, MUG: ABC-conjecture, The ABC Conjecture, The Amazing ABC Conjecture
Catalan Conjecture
Catalan's Conjecture, Catalan's Problem, Math Trek: Conquering Catalan's Conjecture, MathWorld News: Draft Proof of Catalan's Conj, MathWorld: Catalan's Conjecture, Powers Differing By 1 (Catalan), StudyWorks Online : Another Big Conjecture Proved, Wikipedia: Catalan's Conjecture, Zeroing In on Catalan's Conjecture
Collatz Problem
An Image from the Collatz Problem, Collatz 3n+1 Problem Structure, Collatz Problem, Computational Verification of the 3x+1 Conjecture, Experiments with the 3n+1 Sequence, On The 3x + 1 Problem, The 3x + 1 Problem and its Generalizations, The 3x+1 Problem Annotated Bibliography, The 3x+1 Problem Conference Proceedings, The Collatz 3n+1 Conjecture is Unprovable
Goldbach Conjecture
A Simple Solution to the Goldbach Conjecture, An "Expository Proof" of the Goldbach Co, Behaviour of Prime Numbers, Christian Goldbach, Goldbach Conjecture, Goldbach Conjecture Research, Goldbach Conjecture Verification, Goldbach's Conjecture, Goldbach's Conjecture - Recent Progress, Mathematical Mysteries
Advice to Research Students
Some tips for solving problems in number theory, collected by the Cardiff University group.
L-functions and Random Matrix Theory
Conjectures and open problems concerning L-functions, focussing on the areas in which there has been recent progress using results from Random Matrix Theory. Maintained at AIM.
Mathematician's Secret Room
Unsolved problems in Number Theory. English and Japanese text by Hisanori Mishima.
Number Theory Conjectures
A collection of easily stated conjectures which are still open. Each conjecture is stated along with a collection of references.
Open Problems
Some questions compiled by Jon Perry.
Seva Lev's Problem Page
A collection of research problems.
Unsolved Problems and Conjectures
Regarding equal sums of like powers, compiled by Chen Shuwen.
Unsolved Problems and Rewards
By Clark Kimberling. Offers prizes for solutions of some problems in number theory.