Hello Mark,

i wrote a prime sieve with Cuda on a Gpu Geforce 450 with 192 cores.

All work is done on the Gpu.

I get as result only the numbers of primes in arithmetic progressions.

The Programm needs approximately 1 month for counting all primes below 10^15

I am not sure if this is a good result, but i could give you the code,

if you want, it is quite nice and uses not the sieve of Eratosthenes,

but more a sieve of Ulam in some derivated form.

Does it make any sense to calculate the numbers of primes in arithmetic progressions up to 10^15 ?

Nice greetings from the primes

Bernhard