PrimeGrid’s
Factorial Prime Search
On 04 Oct 2010, 15:01:15 UTC, PrimeGrid’s PRPNet found the largest known
Factorial prime:94550!-1
The prime is 429,390 digits long and enters Chris Caldwell's “The Largest Known
Primes Database” (http://primes.utm.edu/primes) ranked 1st for Factorial primes and155th overall.
The discovery was made by Dmitry Domanov of Russia using an Intel Xeon E5310 @1.60GHz with 4GB RAM, running 32 bit Windows 2003 Server. This computer took
about 24 hours and 19 minutes to complete the prime test. Dmitry is a member ofTeam Russia.
The prime was verified on 05 Oct 2010, by an Intel Q6600 @ 2.4 GHz with 2 GB
RAM, running 64 bit Windows XP Professional. This computer took a little over 13hours 45 minutes to complete the prime test.
The credits for the discovery are as follows:
1. Dmitry Domanov (Russia), discoverer
2. PrimeGrid, et al.
3. fsieve/psieve/fpsieve, sieve programs developed by Mark Rodenkirch

and Geoff Reynolds

4. PFGW, primality program developed by Chris Nash & Jim Fougeron
Entry in “The Largest Know Primes Database” can be found here:
http://primes.utm.edu/primes/page.php?id=95248
This is only the 24th known Factorial prime...the 14th discovery in the last 29 years
and the first in over 8 years. Needless to say, this is a very rare find. It more thantriples the size of the previous record of 34790!-1 (142891 digits).
Using a single PC would have taken years to find this prime. So this timely
discovery would not have been possible without the hundreds of volunteers whocontributed their spare CPU cycles. A special thanks to everyone who offered theiradvice and/or computing power to the search - especially Mark Rodenkirch andGeoff Reynolds who were major forces in moving the project forward. Also, thankyou to all the sievers and PRPNet’ers who contributed to this effort.
The Factorial Prime Search will continue to seek even larger primes. To join thesearch please visit PrimeGrid: http://www.primegrid.com

PrimeGrid’s
Factorial Prime Search
About PrimeGrid
PrimeGrid is a distributed computing project, developed by Rytis Slatkevičius, which
utilizes BOINC and PRPNet to search for primes. PrimeGrid's primary goal is to bringthe excitement of prime finding to the "everyday" computer user. Simply download
the software and let your computer do the rest. Participants can choose from avariety of prime forms to search. With a little patience, you may find a large or evenrecord 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 by ateam based at the University 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
PRPNetPRPNet 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 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