PrimeGrid’sExtended Sierpinski Problem Prime Search
On 3 April 2018, 15:55:55 UTC, PrimeGrid’s Extended Sierpinski Problem Prime Search project
found the Mega Prime:11452891
193997*2+1
The prime is 3,447,670 digits long and will enter Chris Caldwell's “The Largest Known Primes
thDatabase” (http://primes.utm.edu/primes) ranked 23 overall. This find eliminates k=193997; 10k's remain in the Extended Sierpinski Problem.
The discovery was made by Tom Greer of the United States using an Intel(R) Xeon(R) E5-2620
v3 CPU @ 2.40GHz with 16GB RAM, running Microsoft Windows 10. This computer took about
3 hours 45 minutes to complete the primality test using multithreaded LLR. Tom is a member of
the Sicituradastra. team.
The prime was verified on 4 April 2018, 00:17:20 UTC by Gary Bauer of the United States using
an Intel(R) Core(TM) i7-8700K CPU @ 3.70GHz with 16GB RAM, running Microsoft Windows
10. This computer took about 2 hours 25 minutes to complete the primality test using
multithreaded LLR.
Credits for the discovery are as follows:
1.
2.
3.
4.
5.

Tom Greer (United States), discoverer
PrimeGrid, et al.
Srsieve, sieving program developed by Geoff Reynolds
LLR, primality program developed by Jean Penné
OpenPFGW, a primality program developed by Chris Nash & Jim Fougeron withmaintenance and improvements by Mark Rodenkirch

Entry in "The Largest Know Primes Database" can be found here:
http://primes.utm.edu/primes/page.php?id=124564
OpenPFGW, a primality program developed by Chris Nash & Jim Fougeron, was used to checkfor Fermat Number divisibility (including generalized and extended). For more information
about Fermat and generalized Fermat Number divisors, please see Wilfrid Keller's sites:• http://www.prothsearch.com/fermat.html• http://www.prothsearch.com/GFNfacs.html
No generalized and extended generalized Fermat number divisors were discovered with thisprime find.
Using a single PC would have taken years to find this prime. So this timely discovery would nothave been possible without the thousands of volunteers who contributed their spare CPUcycles. A special thanks to everyone who contributed their advice and/or computing power tothe search - especially all the sievers who work behind the scenes to make a find like thispossible.
The Extended Sierpinski Problem Prime Search will continue to seek primes for the remaining kvalues. To join the search please visit PrimeGrid: http://www.primegrid.com

PrimeGrid’s
Extended Sierpinski Problem Prime Search
About PrimeGrid
PrimeGrid is a distributed computing project, developed by Rytis Slatkevičius and currently
managed by Iain Bethune, James Breslin, Scott Brown, Ulrich Fries, Michael Goetz, RogerKarpin, Rytis Slatkevičius, and Van Zimmerman.
PrimeGrid utilizes BOINC and PRPNet to search for primes with the primary goal of bringing theexcitement of prime finding to the "everyday" computer user. Simply download the software andlet 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 toparticipate in multiple distributed computing projects through a single program. Currently
BOINC is being developed by a team based at the University of California, Berkeley led
by David Anderson.
This platform currently supports projects from biology to math to astronomy. For moreinformation, please visit BOINC: http://boinc.berkeley.edu
PRPNet
PRPNet is a client/server application written by Mark Rodenkirch that is specificallydesigned 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, wwww, 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