Awesome! Congratulations - and thanks for doing it. Note that I fixed a bug in the b15 version that was breaking things under windows (so it's now called b16) so you might have an easier time getting it running on VS now.
Thank you!
I am quite happy with my flavor of b14. I do some fiddling with prime numbers occasionally and spent a lot of my spare time this summer trying to figure out the sieve. (Part 2 of Fast Prime Cluster Search could have saved some time, but it was an interesting exercise tracking the ingenious code!)
I left out all the xpt and Riecoin block handling, the starting target was simply 2^difficulty, with a smaller random number added. With no Riecoin restrictions, I could use larger primorials. My only other change to the sieve was when I check the five remaining tuplet members for primality, I break the loop at the first non-prime. I know I won't get a full 6-tuplet and searching for a 4 or 5-chain with a "hole" in it is of no use. The mpz_powms in the Fermat tests are quite time consuming!
BTW, while I was thinking about where to go next *) the program was idling away here the other day and (almost accidentally!) found a 600-digit 6-tuplet. I'll stop there and leave the rest to the Riecoin Superblock.
Regards, Vidar
*) Fortunate numbers at present, definitely not Riecoin stuff, probably both impossible and useless, but fun!