About
PrimeGrid's primary goal is to advance mathematics by enabling everyday computer users to contribute their system's processing power towards prime finding. By simply
downloading and installing BOINC and attaching to the PrimeGrid project,
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 and enter into Chris Caldwell's The Largest Known Primes Database with a multi-million digit prime!
PrimeGrid's secondary goal is to provide relevant educational materials about primes. Additionally, we wish to contribute to the
field of mathematics.
Lastly, primes play a central role in the cryptographic systems which are used for computer security. Through the study of prime
numbers it can be shown how much processing is required to crack an encryption code and thus to determine whether current
security schemes are sufficiently secure. PrimeGrid is currently running several sub-projects:
- 321 Prime Search: searching for
mega primes of the form 3·2n±1.
- Cullen-Woodall Search: searching for
mega primes of forms n·2n+1 and
n·2n−1.
- Generalized Cullen-Woodall Search: searching for mega primes of forms n·bn+1 and
n·bn−1 where n + 2 > b.
- Extended Sierpinski Problem: helping solve the Extended Sierpinski Problem.
- Generalized Fermat Prime Search: searching for
megaprimes of the form b2n+1.
- Prime Sierpinski Project: helping the Prime Sierpinski Project solve the Prime Sierpinski Problem.
- Proth Prime Search: searching for primes of the form k·2n+1.
- Fermat Divisor Search: a subset of the Proth Prime Search specificically searching for divisors of
Fermat numbers.
- Seventeen or Bust: helping to solve the Sierpinski Problem.
- Sierpinski/Riesel Base 5: helping to solve the Sierpinski/Riesel Base 5 Problem.
- Sophie Germain Prime Search: searching for primes p and 2p+1.
- The Riesel problem: helping to solve the Riesel Problem.
- AP27 Search: searching for record length arithmetic progressions of primes.
Recent Significant Primes
On 13 August 2020, 17:09:10 UTC, PrimeGrid's Sierpinski/Riesel Base 5 Problem project eliminated k=109838 by finding the mega prime:
109838·53168862-1
The prime is 2,214,945 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 72 nd overall and is the largest known base 5 prime. 62 k's now remain in the Riesel Base 5 problem.
The discovery was made by Erik Veit ( zombie67 [MM]) of the United States using an AMD Ryzen Threadripper 3970X 32-Core Processor with 63GB RAM, running Linux Mint.
This computer took about 6 hours, 14 minutes to complete the primality test using LLR. Erik Veit is a member of SETI.USA.
The prime was verified on 13 August 2020, 22:53:05 UTC by Frederik Schiøler ( Soulfly) of Denmark using an Intel(R) Xeon(R) Gold 6140 CPU @ 2.30GHz with 1GB RAM, running Linux Ubuntu.
This computer took about 11 hours, 52 minutes to complete the primality test using LLR. Frederik Schiøler is a member of Antarctic Crunchers.
For more information, please see the Official Announcement.
On 29 May 2020, 07:52:25 UTC, PrimeGrid's Generalized Fermat Prime Search found the Mega Prime:
3638450524288+1
The prime is 3,439,810 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 3 rd for Generalized Fermat primes and 35 th overall.
The discovery was made by Wolfgang Schwieger ( DeleteNull) of Germany using a GeForce RTX 2070 in an AMD Ryzen 7 3700X 8-Core Processor with 16GB RAM, running Linux openSUSE.
This GPU took about 31 minutes to complete the probable prime (PRP) test using GeneferOCL5. Wolfgang Schwieger is a member of the SETI.Germany team.
The PRP was verified on 29 May 2020, 08:23:51 UTC by Greg Miller ( Olgar) of the United States using an AMD Ryzen Threadripper 2990WX 32-Core Processor with 128GB RAM, running Microsoft Windows 10 Professional x64 Edition.
This computer took about 1 hour, 3 minutes to complete the probable prime (PRP) test using GeneferOCL5. Greg Miller is a member of the USA team.
The PRP was confirmed prime by an Intel(R) Xeon(R) CPU E3-1240 v6 @ 3.70GHz with 4GB RAM, running Linux Debian. This computer took about 1 day, 19 hours, 22 minutes to complete the primality test using LLR.
For more information, please see the Official Announcement.
On 1 May 2020, 04:01:08 UTC, PrimeGrid's Sierpinski/Riesel Base 5 Problem project eliminated k=118568 by finding the mega prime:
118568·53112069+1
The prime is 2,175,248 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 70 th overall and is the largest known base 5 prime. 30 k's now remain in the Sierpinski Base 5 problem.
The discovery was made by Honza Cholt ( Honza) of the Czech Republic using an Intel(R) Core(TM) i7-9700K CPU @ 3.60GHz with 32GB RAM, running Microsoft Windows 10 Professional x64 Edition.
This computer took about 49 minutes to complete the primality test using LLR. Honza Cholt is a member of Czech National Team.
The prime was verified on 2 May 2020, 09:00:41 UTC by Tom Murphy VII ( brighterorange) of the United States using a gfx1010 in an AMD FX-8370 Eight-Core Processor with 16GB RAM, running Microsoft Windows 10 Professional x64 Edition.
This computer took about 1 day, 1 hour, 55 minutes to complete the primality test using LLR.
For more information, please see the Official Announcement.
Other significant primes
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News 
Warning about the end of the challenge
Despite our best efforts, we're not sure the server is going to make it to the end of the challenge. We're not asking people to stop crunching, but we are advising anyone who may be "bunkering" tasks for a competitive push at the end that the server may be unavailable. Please make sure all your tasks are counted by getting them back to the server as soon as possible!
THe challenge discussion thread can be found here: https://www.primegrid.com/forum_thread.php?id=9271
5 Sep 2020 | 10:11:58 UTC
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International Bacon Day Challenge starts September 3rd
In honor of the day arbitrarily chosen by three graduate students at the University of Colorado Boulder to celebrate this notorious breakfast meat, PrimeGrid will be running a 3-day PPSE-LLR challenge from 3 September 00:00 UTC to 6 September 00:00 UTC.
Work units from the Proth Prime Search Extended (LLR) project, which are downloaded and completed during the challenge will count towards your challenge score.
The work units are big enough to earn you a spot on the Top 5000 list if you score a prime, but small enough that your chances are as high as 1 in 30,000 per task! That might not sound like a lot, but an average 4-core CPU can churn out nearly 300 per day. Best of luck!
Inquiries? Inspirations? Introspections? Do you have a finite Bacon Number? Tell us in the forum thread for this challenge: https://www.primegrid.com/forum_thread.php?id=9271
31 Aug 2020 | 4:29:11 UTC
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SR5 Mega Prime!
On 13 August 2020, 17:09:10 UTC, PrimeGrid’s Sierpinski/Riesel Base 5 Problem project eliminated k=109838 by finding the mega prime:
109838*5^3168862-1
The prime is 2,214,945 digits long and enters Chris Caldwell's “The Largest Known Primes Database” ranked 72ns overall and is the largest known base 5 prime. 62 k’s now remain in the Riesel Base 5 problem.
The discovery was made by Erik Veit (zombie67 [MM]) of the United States AMD Ryzen Threadripper 3970X 32-Core Processor with 63GB RAM, running Linux Mint. This computer took about 6 hours, 14 minutes to complete the primality test using LLR. Erik Veit is a member of the SETI.USA team.
The prime was verified on 13 August 2020, 22:53:05 UTC by Frederik Schiøler (Soulfly) of Denmark using an Intel(R) Xeon(R) Gold 6140 CPU @ 2.30GHz with 1GB RAM, running Linux Ubuntu. This computer took about 11 hours, 52 minutes to complete the primality test using LLR. Frederik Schiøler is a member of the Antarctic Crunchers team.
For more details, please see the official announcement.
20 Aug 2020 | 17:56:53 UTC
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Katherine Johnson Memorial Challenge starts July 24th
In honor of the life of Katherine Johnson, PrimeGrid will be running a 7-day TRP-LLR challenge from 24 July 20:00 UTC to 31 July 20:00 UTC. Will we end this subproject's 3-year prime drought?
Also make sure to read Hidden Figures, a book about Katherine Johnson and some of her contemporaries, for the book club meeting!
Doubts? Disputes? Dubieties? Discuss in the forum thread for the challenge: https://www.primegrid.com/forum_thread.php?id=9217
21 Jul 2020 | 3:27:07 UTC
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Alan Turing's Birthday Challenge starts June 23rd
In honor of the 108th birthday of Alan Turing, English mathematician, computer scientist, logician, and more, PrimeGrid will be running a 3-day PPS-Sieve challenge from 23 June 22:00 UTC to 26 June 22:00 UTC!
The challenge subproject is available for both CPU and GPU.
Discuss in the forum post for the challenge: https://www.primegrid.com/forum_thread.php?id=9178
21 Jun 2020 | 22:17:10 UTC
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Newly reported primes(Mega-primes are in bold.)
6973*2^1603226+1 (zunewantan); 196461026^32768+1 (B2lee); 11081688^262144+1 (zombie67 [MM]); 196409928^32768+1 (Johny); 5583460689705*2^1290000-1 (crashtech); 5583209817645*2^1290000-1 (yves); 196354878^32768+1 (catavalon21); 5257*2^1602838+1 ([AF>Occitania] f11ksx); 196299442^32768+1 (WezH); 5582153382855*2^1290000-1 (Gage Schacher); 196272640^32768+1 (jshriver); 20968936^131072+1 (tng); 196231736^32768+1 (Tomiticus); 3333*2^1602968+1 (zunewantan); 196189694^32768+1 (RussEfarmer); 5580352681347*2^1290000-1 (Artist); 5576705997945*2^1290000-1 (duducz); 196170604^32768+1 (Spear); 5579689094787*2^1290000-1 (Viktor Svantner); 5581886383377*2^1290000-1 (mrzorronator) Top Crunchers:Top participants by RAC | Top teams by RAC |
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