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-   -   Operation: Billion Digits (https://www.mersenneforum.org/showthread.php?t=2235)

 ET_ 2004-03-22 13:35

[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

 ET_ 2004-03-22 16:17

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 start-end bits...

Luigi

 ET_ 2004-03-22 22:41

[QUOTE=ET_]I also wrote a version of the program that accepts a batch textfile with exponents and start-end bits...

Luigi[/QUOTE]

Sorry for the auto-quote... 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

 wblipp 2004-03-23 02:59

[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

 wblipp 2004-03-23 03:30

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

 ET_ 2004-03-24 08:09

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

 ET_ 2004-03-26 12:39

[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 far-seeing effort :flex:

Is anybody interested in this work?

Luigi

 ET_ 2004-03-26 13:20

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

 ET_ 2004-03-26 13:32

[code]
M3321928171 no factor from 2^61 to 2^67.
[/code]

Luigi

 Xyzzy 2004-03-26 15:24

[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 far-seeing 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 co-mod over there...

 ET_ 2004-03-26 16:27

[QUOTE=Xyzzy]You could work this with the >79.3M LMH project if you want, let me know and we'll make you a co-mod 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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