Number Sequences by Feather Feet helps you generate prime numbers, numbers from the fibonacci sequence, as well as arithmetic/geometric sequences. It has an intuitive, flowing interface without hidden menus. The prime number sequence generator uses the age-old Eratosthenes Sieve algorithm, which runs faster than the ordinary divide-by-all-numbers algorithm. Last but not least, Number Cruncher costs $0.00, so anybody can use it to help themselves get acquainted with number sequences.