PrimeGrid’sSophie Germain Prime Search
On 29 February 2016 05:39:14 UTC, PrimeGrid’s Sophie Germain Prime Search founda World Record Sophie Germain prime:2618163402417*21290000-1
The prime is 388,342 digits long, eclipsing the previous record of 200,701 digits. It
enters Chris Caldwell's “The Largest Known Primes Database”(http://primes.utm.edu/primes) ranked 1st for Sophie Germain primes and 3,747thoverall.
The discovery was made by Scott Brown of the United States using an Intel(R)Core(TM)2 Quad CPU Q6700 @ 2.66GHz with 4 GB RAM running Microsoft Windows7 Enterprise. This computer, using LLR, took about 1 hour and 33 minutes to complete
the primality test. Scott is a member of the Duke University team.
The prime was verified on 29 February 2016 06:21:47 UTC, by Vaughan Davies ofAustralia using an Intel(R) Core(TM) i7-4770S CPU @ 3.10GHz with 32 GB RAM
running Microsoft Windows 7 Ultimate. This computer, using LLR, took about 47
minutes to complete the primality test. Vaughan is a member of the AMD Users team.
Credits for the discovery are as follows:
1.
2.
3.
4.

Scott Brown (United States), discoverer
PrimeGrid, et al.
TwinGen, sieving program developed by David Underbakke
LLR, primality program developed by Jean Penné

Entry in “The Largest Know Primes Database” can be found here:
https://primes.utm.edu/primes/page.php?id=121331 Sophie Germain (2p+1)
https://primes.utm.edu/primes/page.php?id=121330 Sophie Germain (p)If both p and 2p+1 are prime, then p is a Sophie Germain prime. The first few Sophie
Germain primes are 2, 3, 5, 11, 23, 29, 41, 53, 83, 89, 113, and 131.
The search took a little over 3 years with more than 20,000 users completing a little
over 37 million tests. Over 2,100 single primes were found and added to the Top 5000
list. Just over 26% of the sieved search space was exhausted before the twins werefound. This is PrimeGrid’s 2nd World Record Sophie Germain prime.
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 whocontributed their advice and/or computing power to the search - especially DavidUnderbakke who was instrumental with advice and research. Additional thanks goesto Lennart Vogel for doing the tedious sieve work.

PrimeGrid’sSophie 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.
BOINCThe 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