PrimeGrid’s321 Prime Search
On 13 March 2015 19:55:59 UTC, PrimeGrid’s 321 Prime Search found another
Mega Prime:
3*211731850-1
The prime is 3,531,640 digits long and will enter Chris Caldwell's “The Largest
Known Primes Database” (http://primes.utm.edu/primes) ranked 12th overall.
This is the largest known prime for the 3*2^n-1 form.
The discovery was made by Karsten Klopffleisch of Germany using an Intel(R)Core(TM) i7-2600K CPU @ 3.40GHz with 16 GB RAM running Linux. This
computer took about 18 hours and 33 minutes to complete the primality testusing LLR.
The prime was verified on 18 March 2015 18:17:44 UTC, by Thomas Gbenro ofGermany using an Intel(R) Core(TM) i5-2500 CPU @ 3.30GHz with 4 GB RAM
running Windows 7 Enterprise. This computer took about 12 hours and 16
minutes to complete the primality test using LLR. Thomas is a member of theBOINC@Frankfurt Team.
Credits for the discovery are as follows:
1.
2.
3.
4.

Karsten Klopffleisch (Germany), discoverer
PrimeGrid, et al.
Srsieve, sieving program developed by Geoff Reynolds
LL , primalit program de eloped b ean Penn

Entr in “The Largest Know Primes Database” can be found here:
http://primes.utm.edu/primes/page.php?id=119571
OpenPFGW, a primality program developed by Chris Nash & Jim Fougeron, wasused to check for Fermat Number divisibility (including generalized andextended). For more information about Fermat and generalized Fermat Numberdivisors, please see Wilfrid Keller's sites: http://www.prothsearch.net/fermat.html
 http://www.prothsearch.net/GFNfacs.html
Using a single core PC would have taken decades to find this prime. So thistimely discovery would not have been possible without the thousands ofvolunteers who contributed their spare CPU cycles. A special thanks to everyone
who contributed their advice and/or computing power to the search.
The 321 Prime Search will continue to seek even larger primes. To join thesearch please visit PrimeGrid: http://www.primegrid.com

PrimeGrid’s
321 Prime Search
About PrimeGrid
PrimeGrid is a distributed computing project, developed by Rytis Slatkevičius,Lennart Vogel, and John Blazek, which utilizes BOINC and PRPNet to search forprimes. PrimeGrid's primary goal is to bring the excitement of prime finding to the"everyday" computer user. Simply download the software and let your computer
do the rest. Participants can choose from a variety of prime forms to search. Witha little patience, you may find a large or even record breaking prime.
BOINC
The Berkeley Open Infrastructure for Network Computing (BOINC) is asoftware platform for distributed computing using volunteered computerresources. It allows users to participate in multiple distributed computing
projects through a single program. Currently BOINC is being developed bya team based at the University of California, Berkeley led by DavidAnderson.
This platform currently supports projects from biology to math to astronomy.
For more information, please visit BOINC: http://boinc.berkeley.edu
PRPNet
PRPNet is a client/server application written by Mark Rodenkirch that is
specifically designed to help find prime numbers of various forms. It is easily
ported between various OS/hardware combinations. PRPNet does not run
each PRP test itself, but relies on helper programs, such as LLR, PFGW,
phrot, and genefer to do the work.
For more information, please isit PrimeGrid’s P PNet forum thread:
http://www.primegrid.com/forum_thread.php?id=1215
For more information about PrimeGrid and a complete list of available prime
search projects, please visit: http://www.primegrid.com