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Message boards : Project Staging Area : PrimeGrid partners with 12121 Search

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John
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Message 13574 - Posted: 13 Feb 2009 | 7:19:38 UTC
Last modified: 2 Mar 2012 | 15:20:05 UTC

27121 Prime Search

PrimeGrid and 12121 Search are now collaborating in an effort to find a Mega Prime of the form 121*2^n-1. This is very similar to the 321 Prime Search at k=3.

12121 Search was established on 5/24/2004 to search for large primes of the form 121*2^n-1. Later (3/1/2005), they added k=27 to their search. Their "short term" goal is to search for n up to 10M. For more information, please visit their site: 12121 Search.

As we did with 321, we are going to test the +1 form of these k's in parallel as well. Therefore, the effort will consist of the following:

121*2^n+1, 121*2^n-1
27*2^n+1, 27*2^n-1

for n<10M

First order of business is to establish a coordinated sieving effort to bring all forms to the same depth. Here's the current status:

COMPLETED wrote:
121 -1 at p=290T for n<10M
121 +1 at p~450T for n<5M and p=1T for 5M<n<10M
27 -1 at p=130T for n<10M
27 +1 at p~450T for n<5M and p=1T for 5M<n<10M

We need two efforts but we'll only focus on one right now:

1. Primary focus - 27 -1 to bring it up to p=290T then combine with 121 to take to 450T
2. 121 & 27 +1 for 5M<n<10M to bring it up to 450T.

Current progress can be found in the manual sieve reservations. To participate, please see 12121 Sieving Reservation.

Second order of business is to primality test 27 -1, 27 +1, and 121 +1 up to n~3.7M to combine it with 121 -1. Therefore, candidates will be available for testing in PrimeGrid's PRPNet. If you are interested in participating, please see the PRPNet thread. Port 5000 is currently loaded with 27 & 121 +1 for 600K<n<1.7M.

Again, welcome to 27121 Prime Search and the chance of finding another Mega Prime!!! :)
____________

John
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Message 19741 - Posted: 13 Dec 2009 | 16:18:51 UTC
Last modified: 26 Dec 2009 | 5:33:09 UTC

Megabit Prime for 12121 Search

On 4 Dec 2009, PrimeGrid, in collaboration with 12121 Search, found a megabit prime: 27*2^1902689-1. The prime is 572,768 digits long and enters Chris Caldwell's The Largest Known Primes Database ranked 76th overall.

The discovery was made by Peter Kaiser of Germany using a dual Intel Xeon X5472 @3.0GHz with 16GB RAM. This computer took 59 minutes and 17 seconds to complete the primality test. Peter is a member of the team SETI.Germany.

This is the 63rd overall prime for k=27 and the 5th prime found by the 12121 Search. Other 12121 Search primes for k=27 are:

3/23/2008 - 27*2^1108214-1 Arnold Padro
11/01/2005 - 27*2^777992-1 James Burt
7/14/2005 - 27*2^729314-1 William W. Mikrut
3/31/2005 - 27*2^627794-1 Chris Chatfield

Complete list of n in which 27*2^n-1 is prime:

1, 2, 4, 5, 8, 10, 14, 28, 37, 38, 70, 121, 122, 160, 170, 253, 329, 362, 454, 485, 500, 574, 892, 962, 1213, 1580, 2642, 2708, 4505, 8152, 11858, 13300, 15041, 16118, 16778, 19069, 22769, 29020, 30298, 30377, 35942, 42817, 42869, 62024, 74629, 90449, 91042, 117901, 128594, 143330, 152530, 157898, 175852, 282700, 340682, 444622, 627794, 729314, 777992, 1108214, 1163629, 1253870, (...) 1902689
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John
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Message 19742 - Posted: 13 Dec 2009 | 16:29:43 UTC

Status Update

Sieving for the 4 forums (121*2^n+1, 121*2^n-1, 27*2^n+1, 27*2^n-1) for n<10M has reached p=1220T.

There only a few thousands tests remaining below 2M. We hope to have that completed by the end of the year.

Basic Stats: for PRPNet
port 12006: 27121 Server : User
____________

John
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Message 20119 - Posted: 26 Dec 2009 | 6:14:01 UTC
Last modified: 26 Dec 2009 | 6:22:52 UTC

Megabit Prime for 27121 Search

On 23 Dec 2009, PrimeGrid's PRPNet found a megabit prime: 27*2^2218064+1. The prime is 667,706 digits long and enters Chris Caldwell's The Largest Known Primes Database ranked 56th overall.

The discovery was made by Honza Cholt (Honza) of the Czech Republic using a dual Intel Xeon @ 3.06GHz with 4GB RAM. This computer took 2 hours 38 minutes and 59 seconds to complete the primality test. Honza is a member of the team BOINC.SK.

This is the 45th overall prime for k=27 +1 and the 1st found by PrimeGrid. This form has now been searched to n=2M. (x)gfn divisibility testing is currently underway.

Complete list of n in which 27*2^n+1 is prime:

2, 4, 7, 16, 19, 20, 22, 26, 40, 44, 46, 47, 50, 56, 59, 64, 92, 175, 215, 275, 407, 455, 1076, 1090, 3080, 3322, 6419, 7639, 19360, 30500, 38770, 44164, 50696, 114760, 117784, 153847, 160874, 178739, 379880, 405514, 672007, 974752, 1164664, 1476347, 2218064 [2000000]
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[SG]Puzzle-Peter
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Message 20120 - Posted: 26 Dec 2009 | 6:19:58 UTC

Congratulations Honza!
____________
There are only 10 kinds of people - those who understand binary and those who don't

geeknik

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Message 20137 - Posted: 27 Dec 2009 | 5:09:20 UTC - in response to Message 20119.

Congrats to Honza and PrimeGrid. That was a nice Christmas present for the project! :)
____________
FUCK THIS PROJECT AND THEIR COMMIE BULLSHIT POLITICS

Honza
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Message 20185 - Posted: 28 Dec 2009 | 18:52:36 UTC

Thanks.

Machine (already retired server) was about to be shut-downed for good one the very same day it found the prime!

____________
My stats
Badge score: 1*1 + 5*1 + 8*3 + 9*11 + 10*1 + 11*1 + 12*3 = 186

Odicin

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Message 50499 - Posted: 26 Feb 2012 | 15:17:05 UTC

Congrats@Pooh_Bear_27 for this huge found ranked at 28th overall...

http://primes.utm.edu/primes/page.php?id=105070

Regards Odi
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Honza
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Message 50503 - Posted: 26 Feb 2012 | 15:51:38 UTC

Congrats!

btw, PG now has 34 primes at Top100 rank.
____________
My stats
Badge score: 1*1 + 5*1 + 8*3 + 9*11 + 10*1 + 11*1 + 12*3 = 186

Pooh Bear 27

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Message 50509 - Posted: 26 Feb 2012 | 16:21:53 UTC

Thanks everyone. I now have two awesome finds. The largest Twin Prime and now the first 121 since it's been on the PG project.

Neo
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Message 50518 - Posted: 26 Feb 2012 | 16:54:23 UTC

Ditto.

That's a nice find!

Neo
AtP

Michael Goetz
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Message 50524 - Posted: 26 Feb 2012 | 17:21:35 UTC

Congratulations!!!
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Wabbit98

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Message 50543 - Posted: 26 Feb 2012 | 19:30:28 UTC

Now hopefully the next 121 is not 6 years away.

Ni
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Message boards : Project Staging Area : PrimeGrid partners with 12121 Search