Patterns by Harvey Heinz. http://www.geocities.com/dhvanderstraten/ulamtxt.html . Ulam's Spirals: Towards an Explanation by Didier van der Straten. http://www.troubleshooters.com/codecorn/primenumbers/primenumbers.htm . "Fun With Prime Numbers" Wikipedia on Math Math , Areas of mathematics , and List of lists of mathematical topics . Help:Formula . For entering formulas in Wiki articles. Algebra Algebra of sets