PrimeGrid’s321 Prime Search
On 5 July 2023, 17:48:23 UTC, PrimeGrid's 321 Prime Search found the Mega Prime:3*220928756 - 1
The prime is 6,300,184 digits long and will enter “The Largest Known Primes Database”(https://t5k.org/primes) ranked 19th overall. This is the largest known prime for the 3*2^n1 form.
The discovery was made by Arno Lehmann of Germany using an AMD Ryzen 9 7900X@ 4.7GHz with 64GB RAM, running Debian GNU/Linux 12 (bookworm). This CPU took
about 6 hours, 20 minutes to complete the probable prime (PRP) test using LLR2.
The PRP was confirmed prime on 5 July 2023 by an AMD Ryzen 9 7900X @ 4.7GHz,
running Arch Linux. This computer took about 2 hours, 46 minutes to complete theprimality test using LLR2.
The credits for the discovery are as follows:
1.
2.
3.
4.
5.

Arno Lehmann (Germany), discoverer
PrimeGrid, et al.
Srsieve, sieving program developed by Geoff Reynolds
PSieve, sieving program developed by Ken Brazier and Geoff Reynolds
LLR, primality program developed by Jean Penné
6. LLR2, primality program developed by Pavel Atnashev
Entry in “The Largest Known Primes Database” can be found here:
https://t5k.org/primes/page.php?id=136240
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 who contributed theirspare CPU cycles. A special thanks to everyone who offered their advice and/orcomputing power to the search - especially Yves Gallot, Iain Bethune, David
Underbakke, Anand Nair, Mark Rodenkirch and Geoff Reynolds who were major forcesin moving the project forward. Also, thank you to all the sievers, especially Honza Choltand Jim Breslin. A final thanks to Michael Goetz for porting to BOINC.
The 321 Prime Search will continue to search for more primes To join the search please
visit PrimeGrid: https://www.primegrid.com

PrimeGrid’s
321 Prime Search
About PrimeGrid
PrimeGrid is a distributed computing project, developed by Rytis Slatkevičius andcurrently managed by Tyler Bredl, Scott Brown, Michael Goetz, Michael Gutierrez,Darren Li, Dao Heng Liu, Reginald McLean, Rytis Slatkevičius, Roman Trunov, andChristian Wallbaum.
PrimeGrid utilizes BOINC and PRPNet to search for primes with the primary goal ofbringing 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 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 a software
platform for distributed computing using volunteered computer resources. It allows
users to participate in multiple distributed computing projects through a single
program. Currently BOINC is being developed by a team based at the University ofCalifornia, Berkeley led by David Anderson.
This platform currently supports projects from biology to math to astronomy. For
more information, please visit BOINC: https://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, butrelies on helper programs, such as LLR, PFGW, phrot, wwww, and genefer to dothe work.
For more information, please visit PrimeGrid’s PRPNet forum thread:

https://www.primegrid.com/forum_thread.php?id=1215
For more information about PrimeGrid and a complete list of available prime search
projects, please visit: https://www.primegrid.com