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Old 2010-03-07, 22:51   #56
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Default (2^4031399+1)/3

Nice find indeed. Tony deserves a congratulation, putting in many of the CPU cycles in order to find this mega-prp. Congrats to Vincent too, for looking after the baby. I have November to look forward to when my current batch finishes.

1,213,572 decimal digits

Thanks also to Jean Penne for the "LLR" program

Last fiddled with by paulunderwood on 2010-03-07 at 23:26
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Old 2010-03-07, 23:09   #57
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Quote:
Originally Posted by Paul Bourdelais View Post
Congratulations on your discovery and I hope you extend the search. Once the large gap is verified, I would suspect another larger PRP is not too far (p<5500000) since these primes tend to occur in pairs after such large gaps, but of course no gaurantees. I have nearly completed a search for all Repunit PRPs with bases from -11 to 11 up to a base 10 length of 250,000 digits. Good Luck!
We are praying much harder than you for this to be true :)

Vincent
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Old 2010-03-07, 23:21   #58
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Quote:
Originally Posted by paulunderwood View Post
Nice find indeed. Tony deserves a congratulation, putting in many of the CPU cycles in order to find this mega-prp. Congrats to Vincent too, for looking after the baby. I have November to look forward to when my current batch finishes.

1,213,572 decimal digits
4 chinese billion bits in size (*)

If that isn't really big i wouldn't know what is big!

* In Europe for example in The Netherlands a billion (biljoen) is 10^12, for the chinese definition you need to take 2 hops westwards, first to US, pay import tax, then same thing for China.
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Old 2013-03-09, 15:40   #59
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Is the search for wagstaff primes active?

A few years ago I did some trial factoring on wagstaff numbers with LLR on some machines at work. I didn't really have a specific goal in mind and eventually I lost interest and didn't do anything with the factors I found.

I just found the factors on my old harddrive and thought someone might have a use for them:
1,750,064 factors of (2^p+1)/3 for p<50M: wagstaff-factors.zip (15Mb)

I trialfactored: 10k<p<1M to 56bit, 1M<p<2M to 57bit, 2M<p<4M to 58bit, 4M<p<8M to 59bit, 8M<p<16M to 60bit, 16M<p<32M to 61bit, 32M<p<50M to 62bit. For p<10k I did some work with GMP-ECM and I also copied some factors from factordb.com to my list.

I thought about adding all the factors to factordb.com, but I'm not sure if they are interested and I don't know how to add them in batches.

Last fiddled with by ATH on 2013-03-09 at 15:45
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Old 2013-03-09, 17:46   #60
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Originally Posted by ATH View Post
Is the search for wagstaff primes active?
Yes We are current testing Wxxxxxxxx. Vincent has TF'd to 61 bits. We are investigating TF on GPUs. We use mprime/Prime95 for P-1. Please pm me for a chat about possibly uniting with us.

Last fiddled with by paulunderwood on 2013-03-09 at 17:55
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Old 2013-03-09, 18:21   #61
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I'm still hoping someone would soon prove the Reix-Vrba conjecture!
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Old 2013-03-09, 18:44   #62
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Originally Posted by paulunderwood View Post
Yes We are current testing Wxxxxxxxx. Vincent has TF'd to 61 bits. We are investigating TF on GPUs. We use mprime/Prime95 for P-1. Please pm me for a chat about possibly uniting with us.
I don't have that job anymore unfortunately, so I don't have many resources now, I only have my own 2 computers, and I'm not actively working on this atm. But assuming your progress is below 50M you can use some of my factors to eliminate future candidates up to 50M and then trial factor the remaining exponents from my limits up to 61 bit or whatever you choose.

Last fiddled with by ATH on 2013-03-09 at 18:45
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Old 2013-03-09, 22:43   #63
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Quote:
Originally Posted by ATH View Post
Is the search for wagstaff primes active?

A few years ago I did some trial factoring on wagstaff numbers with LLR on some machines at work. I didn't really have a specific goal in mind and eventually I lost interest and didn't do anything with the factors I found.

I just found the factors on my old harddrive and thought someone might have a use for them:
1,750,064 factors of (2^p+1)/3 for p<50M: wagstaff-factors.zip (15Mb)

I trialfactored: 10k<p<1M to 56bit, 1M<p<2M to 57bit, 2M<p<4M to 58bit, 4M<p<8M to 59bit, 8M<p<16M to 60bit, 16M<p<32M to 61bit, 32M<p<50M to 62bit. For p<10k I did some work with GMP-ECM and I also copied some factors from factordb.com to my list.

I thought about adding all the factors to factordb.com, but I'm not sure if they are interested and I don't know how to add them in batches.
Give me an email at diep@xs4all.nl then i'll put you in the reply to to everyone busy with Wagstaff search at this point.

We're busy around 9M now and i TF'ed everything to 61 or 62 bits up to 25M at 2010, we're busy setting up gpgpu TF thanks to Oliver who has been so kind to add it. First results seems we can go to 69 bits, we'll test and debug things more there coming weeks when i manage to get the Tesla's setup for it.

Last fiddled with by diep on 2013-03-09 at 22:44
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Old 2013-03-09, 22:54   #64
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Quote:
Originally Posted by diep View Post
Give me an email at diep@xs4all.nl then i'll put you in the reply to to everyone busy with Wagstaff search at this point.

We're busy around 9M now and i TF'ed everything to 61 or 62 bits up to 25M at 2010, we're busy setting up gpgpu TF thanks to Oliver who has been so kind to add it. First results seems we can go to 69 bits, we'll test and debug things more there coming weeks when i manage to get the Tesla's setup for it.
Correction: the run was to 25M but it never got there. Must lookup until where it got. 12M or 13M the TF reached back in 2010 (TF'ed at 22-24 cores back then) so we're very interested in the results you have to merge the factors for future ranges.

Everything above 1.2M i TF'ed to 61 or 62 bits. Majority 61 bits.
TF is very rewarding for Wagstaff. Don't have exact statistics at hand for Mersenne,
but the TF percentage at 61 bits is already above 60%.

Isn't mersenne getting to similar depth there a 50% TF rate roughly?

Of course one small problem so far: last probable prime we had was in the 4M range...

Last fiddled with by diep on 2013-03-09 at 22:58
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Old 2013-03-10, 03:17   #65
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Quote:
Originally Posted by ATH View Post
1,750,064 factors of (2^p+1)/3 for p<50M

I thought about adding all the factors to factordb.com, but I'm not sure if they are interested and I don't know how to add them in batches.
I suggest an email to Syd about the factors. He may add them for you. His address is on the imprint page linked at the bottom of every factordb page.

Alternatively, you can build these into lines of (2^p+1)/3=factor. You can paste 5-10K lines at a time into the Report Results page. But if most of the factors are unknown, you will quickly hit the limit of 20,000 id's per hour, and need a lot of time to load them all.
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Old 2013-03-10, 13:32   #66
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Quote:
Originally Posted by wblipp View Post
I suggest an email to Syd about the factors. He may add them for you. His address is on the imprint page linked at the bottom of every factordb page.

Alternatively, you can build these into lines of (2^p+1)/3=factor. You can paste 5-10K lines at a time into the Report Results page. But if most of the factors are unknown, you will quickly hit the limit of 20,000 id's per hour, and need a lot of time to load them all.
Ah thanks. That was the info I was missing, I tried space and tab between (2^p+1)/3 and the factor instead of =, I might try that.

Last fiddled with by ATH on 2013-03-10 at 13:32
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