Number Theory Lectures & Articles

(Corollaries from) Pythagoras' Theorem
http://www.cut-the-knot.org/pythagoras/corollary.shtml

Infinite Products

http://www.math.ucsb.edu/~mckernan/Teaching/02-03/Autumn/202A/l_26.pdf

Lucas Number

http://mathworld.wolfram.com/LucasNumber.html

Scrambled Equations

http://www.rinkworks.com/brainfood/p/eq1.shtml

24 Game

http://en.wikipedia.org/wiki/24_Game

The Fundamental Theorem of Arithmetic

http://www.dpmms.cam.ac.uk/~wtg10/FTA.html

The Prime Pages

http://primes.utm.edu/

Infinity and infinities

http://www.gap-system.org/~john/analysis/Lectures/L4.html