Science, Math, Number Theory, Prime Numbers - Number Spiral. Explains this method of visually representing the distribution of primes and the relationships between factors and products.
Science, Math, Number Theory, Prime Numbers - The Prime Puzzles Problems Connection. Carlos Rivera's collection of problems and puzzles related to prime numbers.
Science, Math, Number Theory, People - Nicely, Thomas R.. Computations on primes, prime gaps, prime constellations (twins, triplets, and quadruplets) and their reciprocal sums (to extrapolate estimates for the corresponding Brun's constants).
Science, Math, Number Theory, Factoring - The Factor Zone. Aimed at grade school students and teachers, includes course guidelines, worksheets, and factor tables up to 600.