[QUOTE=wblipp]
What methods are you using to filter the k values before determining 2kp+1? We only need to test prime values of 2kp+1, so various sieving methods are possible. [/QUOTE] I'm checking factors mod 120 instead of 1 or 7 mod 8, and apply primality checking up to (around) 7000. Checking for higher factors would slow subsequent modulo operations on the Mersenne number even if it gets a higher number of K sieved out.. I am still working on source code to translate it into English and eliminate debug calls. Two people have already asked me for the source, if you are interested I can send it to you also. Meanwhile I will take the range of 3,321,928,171 a bit (or two...) further. Finally, I would like to thank Andreas Pipp's work (Andi314): he prompted me towards the right path with his program using Crandall libraries. Luigi 
3,321,928,171 no factor up to 63.001 bits, k=1,391,351,436
Going up to 67 bits... BTW, I also wrote a version of the program that accepts a batch textfile with exponents and startend bits... Luigi 
[QUOTE=ET_]I also wrote a version of the program that accepts a batch textfile with exponents and startend bits...
Luigi[/QUOTE] Sorry for the autoquote... editing is disabled :unsure: I mean, we may have a batch of "billion" exponents and try them up to (say) 58 bits to gather some more fators and play with them. Luigi 
[QUOTE=ET_]3,321,928,171 no factor up to 63.001 bits, k=1,391,351,436
Going up to 67 bits... [/QUOTE] The next two primes have easy factors M( 3321928189 )C: 312261249767 M( 3321928189 )C: 43284724302671 M( 3321928217 )C: 1166521668825287 But M(3321928217) is also stubborn. If you send the program, I'll start a machine on trial factoring this one. William 
Should be:
But M(332192821[b]9[/b]) is also stubborn. If you send the program, I'll start a machine on trial factoring this one. William 
3,321,928,171 no factor up to 66.034 bits, k>11,000,000,000
Still going up to 67 bits... and working with an old 250 MHz PII. William, I'll repost my program as soon as I implement a stronger resuming algorithm (by the end of the week) Luigi 
[QUOTE=ET_]William, I'll repost my program as soon as I implement a stronger resuming algorithm (by the end of the week)
Luigi[/QUOTE] And here it is :smile: Many thanks to Nick Fortino who implemented a trick to gain another 5% of speed :banana: Factor3_1 now can use the r switch to resume from his status.txt file. Now a question: I have a batch version of this program, and a list of about 3300 prime exponents starting from 3321928241,1,50 and ending with 3321999991,1,50 to feed it. We could start a *real* "Billion Project", sieving those exponents up to 50 bits, sending factors to Will Edgington and factoring deeper the tough ones. I could coordinate the ranges and the found factors. We won't find any prime number this way, but projects starting in the next 10 years will have to use our farseeing effort :flex: Is anybody interested in this work? Luigi 
1 Attachment(s)
[QUOTE=ET_]And here it is :smile: [/QUOTE]
I say HERE it is. Due to a small glith in the previous version, here is the REAL one to download. Xyzzy may you please cancel the file attached to the previous post? :innocent: Luigi 
[code]
M3321928171 no factor from 2^61 to 2^67. [/code] Luigi 
[QUOTE=ET_]I could coordinate the ranges and the found factors. We won't find any prime number this way, but projects starting in the next 10 years will have to use our farseeing effort :flex:[/QUOTE]You could work this with the >79.3M LMH project if you want, let me know and we'll make you a comod over there...

[QUOTE=Xyzzy]You could work this with the >79.3M LMH project if you want, let me know and we'll make you a comod over there...[/QUOTE]
That sounds great! I guess someone has the full list of found exponents, their factors and their bit depth... we could accomodate the results on a web page. :lol: Luigi 
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