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Old 2005-08-27, 04:28   #34
lsoule
 
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Nov 2004
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For Sohpie Germain (where p and 2p+1 are both prime), the k*2^n-1 form
is nice. Multiply out 2p+1 and you get k*2^(n+1)-1. So if a (k n)
pair is prime, you only have to check (k n+1)...which will be checked
in this kind of search anyhow.

-Larry
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Old 2005-08-29, 15:28   #35
ValerieVonck
 
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Mar 2004
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330to333.txt
333to336.txt

No primes found.
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Old 2005-08-29, 17:24   #36
Templus
 
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288to291.txt completed

1 prime found! => 355424355*2^290670-1 is prime!

This prime has been reported to the database

taking 363to366.txt
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Old 2005-08-31, 12:13   #37
lsoule
 
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Taking 366-369
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Old 2005-09-03, 04:06   #38
Kosmaj
 
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360-363 complete, no primes.
Taking 369-372.

New files for n>375k will be available soon.
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Old 2005-09-05, 08:45   #39
Cruelty
 
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It looks like finally PIES will take the first place
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Old 2005-09-05, 14:37   #40
fatphil
 
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Quote:
Originally Posted by Cruelty
It looks like finally PIES will take the first place
My bet is that, given that it took over a month to go from 1 fewer to equal (via 10 fewer a couple of times), we'll be swapping places many times in the next few months.

Good luck to you all - I do look forward to seeing your densest candidates yielding more primes, as those who are familiar with my past prime number projects will attest.

Phil
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Old 2005-09-07, 03:16   #41
Kosmaj
 
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Taking also 372-375.

Phil
Thanks for your visit! We wish you good luck too! Soon, our small primes on the list will begin dropping out and then I'm afraid we won't be able to keep pace with you. But we'll try to catch up a few months later when your small primes begin dropping...

Kosmaj (a retired drag racer)
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Old 2005-09-07, 10:13   #42
TTn
 

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Looks like we need some more members...
I'll see what I can do about that.
 
Old 2005-09-07, 12:17   #43
lsoule
 
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Default First place again

We're first again with a lead of 2 primes.....for now.
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Old 2005-09-07, 13:21   #44
fatphil
 
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Quote:
Originally Posted by Kosmaj
Taking also 372-375.

Phil
Thanks for your visit! We wish you good luck too! Soon, our small primes on the list will begin dropping out and then I'm afraid we won't be able to keep pace with you. But we'll try to catch up a few months later when your small primes begin dropping...

Kosmaj (a retired drag racer)
I was searching on these fora for a post from Mark R. regarding the speed of PIES on Apple G5 machines, and it was pure luck (not really, my search term including 'PIES') that I encountered this thread - I'm not a forum user really, I find them a bit clumsy. It appears that you noticed my 'threat' before I even noticed the possibility of getting past you!

I don't know how closely you (collectively) have been checking your smallies, but even though you've only got a few thousand digits of margin for many of your primes, you've actually got quite a bit of short-term security. There are several huge bands of similarly sized (proth/riesel) primes that are a very useful buffer for you. So the sharp drop will be quite a while away.

However, that drop will not compare in magnitude with the absolute annihilation that will hit PIES a year or so later. I have deliberately aimed my new subprojects, using a new DWT algorithm, at exclusively >100000-digit primes (the algorithm could flood the 60-100k-digit zone too, but there are so many testable candidates I thought I should be more selective), which means that, but the time we're finished, probably half of the primes in the 100-103kdigit range will be PIES. That will _hurt_ as they drop off.

The linear (by size, exponential by number) growth of the 15k+1 candidates saves you from such harsh drops. We'll no doubt zoom (downwards) past each other several times in the future, and then have to fight our way back up again!

Amusingly, when a current _long_ overdue mini-project (should have taken 2 months, now taken over 4 months on a single machine) finally drops a prime, I may well grab a 15k range and join you for a quick spell!

Until then, I shall enjoy the little dance we're having (you're 3 ahead again, I see, thanks to Larry's recent submissions).

Phil
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