This is a fast program to generate Mersenne Primes. The list "Mersenne Prime N" shows the prime n in the function 2^n -1, which is also prime, and the list "primes" simply shows the primes that have been checked. To make this MUCH faster, download it and run it using Turbo mode(shift-click on Extras, click 'set stepping speeed...' then click Turbo. And no, you probably won't find the 45th Mersenne prime,2^43102609 -1, using this program.
