Thanks for all the info.
I've been playing around with everything a little bit and I have a few more questions:
 This pgfw script seem to be made for Sierpinski only, is there a Riesel one available too?
 covering.exe you a conjectured K and the primes considered to calculate the conjectured K, but it doesn't tell which primes are used when a solution is found. How do I calculate which primes are used for the covering set?
