PrimeGridʼsSophie Germain Prime Search
On 25 Dec 2011 13:31:28 UTC, PrimeGrid’s Sophie Germain Prime Search found
World Record twin primes:3756801695685*2666669± 1
Twin Primes are pairs of primes which differ by two. The first twin primes are{3,5}, {5,7}, {11,13} and {17,19}. It has been conjectured (but never proven) that
there are infinitely many twin primes.

The twin primes are 200,700 digits long, eclipsing the previous record of 100,355
digits. They will enter Chris Caldwell's “The Largest Known Primes Database”(http://primes.utm.edu/primes) ranked 1st for twins.
The discovery was made by Timothy D. Winslow of the United States using an Intel
Core i7 920 @ 2.67GHz with 8 GB RAM running Windows 7 Ultimate. This computer,using LLR, took 26 minutes to complete the primality tests of both primes. Timothy is amember of The Knights Who Say Ni! team.
The prime was verified on 26 Dec 2011 1:58:19 UTC, by Brage E. Elliott of the UnitedStates using an Intel Intel Q8400 @ 2.66GHz with 4 GB RAM running Linux. Thiscomputer, using LLR, took 28 minutes and 42 seconds to complete the primality testsof both primes. Brage is a member of the USA team.
Credits for the discovery are as follows:
1. Timothy D. Winslow
2. PrimeGrid, et al.
3. TwinGen, sieving program developed by David Underbakke
4. LLR, primality program developed by Jean Penné
Entry in “The Largest Know Primes Database” can be found here:
http://primes.utm.edu/primes/page.php?id=103791 twin (p+2)
http://primes.utm.edu/primes/page.php?id=103792 twin (p)The search took almost 2 1⁄2 years with 20,344 users completing just over 25.5 milliontests. Over 3000 single primes were found...~2900 of these were added to the Top
5000 list. Almost 79% of the sieved search space was exhausted before the twins werefound. This is PrimeGrid’s 3rd World Record twin primes.
The search effort would have taken hundreds of years on a fast single core PC.
Therefore, this timely 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 - especially David
Underbakke who was instrumental with advice and research. Additional thanks goesto Lennart Vogel for doing the tedious sieve work.
The Sophie Germain Prime Search will continue to search the remainder of the sieved
search space to hopefully find a Sophie Germain Prime. To join the search please visit
PrimeGrid: http://www.primegrid.com

PrimeGridʼsSophie Germain 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 for primes.
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. With a little patience,
you may find a large or even record breaking prime.
BOINC
The Berkeley Open Infrastructure for Network Computing (BOINC) is a software
platform for distributed computing using volunteered computer resources. It
allows users to participate in multiple distributed computing projects through asingle program. Currently BOINC is being developed by a team based at theUniversity of California, Berkeley led by David Anderson.
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, andgenefer to do the work.
For more information, please visit PrimeGrid’s PRPNet 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