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 as
a Titan!
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.
- 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 Prime Sierpinski Project solve the Prime Sierpinski Problem.
- Proth Prime Search: searching for primes of the form k·2n+1.
- 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.
Recent Significant Primes
On 15 September 2017, 11:01:15 UTC, PrimeGrid's PPS Mega Prime Search project found the mega prime:
1127·23427219+1
The prime is 1,031,699 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 203 rd overall.
The discovery was made by Randall Scalise ( Randall J. Scalise) of the United States
using an Intel(R) Core(TM) i5-4590 CPU @ 3.30GHz with 6 GB RAM, running Linux. This computer took about 1 hour and 13 minutes to complete the primality test using LLR.
For more information, please see the Official Announcement.
On 5 September 2017, 08:23:41 UTC, PrimeGrid's AP27 Search (Arithmetic Progression of 27 primes) found the progression of 26 primes:
48277590120607451+37835074*23#*n for n=0..25
It is the 7th known AP26 known to exist, and the fourth found at PrimeGrid.
The discovery was made by Bruce E. Slade ( Renix1943) of the United States
using an NVIDIA GTX 970 GPU in an Intel(R) Core(TM) i3-6100 @ 3.70GHz CPU with 16GB RAM, running Microsoft Windows 10 Core Edition. This GPU took about 41 minutes to process the task (each task tests 100 progression differences of 10 shifts each).
Bruce is a member of the Aggie The Pew team.
For more information, please see the Official Announcement.
On 29 August 2017, 14:15:23 UTC, PrimeGrid's Generalized Fermat Prime Search found the Generalized Fermat mega prime:
9194441048576+1
The prime is 6,253,210 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 1 st for Generalized Fermat Primes and 12 th overall.
This is the first Generalized Fermat prime found for n=20, the second-largest prime found by PrimeGrid, and the second-largest known non-Mersenne prime.
The discovery was made by Sylvanus A. Zimmerman ( Van Zimmerman) of the United States
using an Nvidia GeForce GTX 1060 in an Intel(R) Xeon(R) E3-1225 v3 CPU at 3.20GHz with 8GB RAM, running Microsoft Windows 10 Professional Edition. This GPU took about 4 hours and 43 minutes to complete the probable prime (PRP) test using GeneferOCL4.
Sylvanis is a member of the Aggie The Pew team.
For more information, please see the Official Announcement.
On 30 August 2017, 13:17:35 UTC, PrimeGrid's Generalized Fermat Prime Search found the Generalized Fermat mega prime:
47090246131072+1
The prime is 1,005,707 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 24 th for Generalized Fermat Primes and 247 th overall.
The discovery was made by Roman Voskoboynikov ( rvoskoboynikov) of the United States
using an Nvidia GeForce GTX 1050 Ti in an Intel(R) Core(TM) i5-4670 CPU at 3.40GHz with 16GB RAM, running Microsoft Windows 10 Professional Edition. This GPU took about 16 minutes to complete the probable prime (PRP) test using GeneferOCL2.
For more information, please see the Official Announcement.
On 25 August 2017, 04:39:57 UTC, PrimeGrid's Sierpinski/Riesel Base 5 Problem project eliminated k=171362 by finding the mega prime:
171362·52400996-1
The prime is 1,678,230 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 57 th overall. 73 k's now remain in the Riesel Base 5 Problem.
The discovery was made by Frank Schwegler ( Frank Schwegler) of the United States
using an Intel(R) Core(TM) i7-5820K CPU @ 3.30GHz with 16GB RAM running Microsoft Windows 7 Ultimate Edition. This computer took about 40 hours and 12 minutes to complete the primality test using LLR.
For more information, please see the Official Announcement.
On 24 August 2017, 11:36:16 UTC, PrimeGrid's PPS Mega Prime Search project found the mega prime:
1119·23422189+1
The prime is 1,030,185 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 200 th overall.
The discovery was made by Jochen Beck ( dh1saj) of Germany
using an Intel(R) Core(TM) i5-4670 CPU @ 3.40GHz with 8GB RAM, running Microsoft Windows 7 Professional Edition. This computer took about 1 hours and 19 minutes to complete the primality test using LLR.
Jochen is a member of the SETI.Germany team.
For more information, please see the Official Announcement.
On 21 August 2017, 14:51:43 UTC, PrimeGrid's Generalized Cullen/Woodall Prime Search project found the largest known generalized Cullen prime:
1341174·531341174+1
The prime is 2,312,561 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 1 st for generalized Cullen primes and 30 th overall.
The discovery was made by Hiroyuki Okazaki ( zunewantan) of Japan
using an Intel(R) CPU @ 2.90GHz with 16GB RAM, running Linux. This computer took about 12 hours and 39 minutes to complete the primality test using multithreaded LLR.
Hiroyuki is a member of the Aggie The Pew team.
For more information, please see the Official Announcement.
On 18 August 2017, 19:28:05 UTC, PrimeGrid's PPS Mega Prime Search project found the mega prime:
1005·23420846+1
The prime is 1,029,781 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 199 th overall.
The discovery was made by Łukasz Piotrowski ( stiven) of Poland
using an Intel(R) Xeon(R) E3-1220 v3 CPU @ 3.10GHz with 4GB RAM, running Linux. This computer took about 1 hours and 1 minute to complete the primality test using LLR.
Łukasz is a member of the BOINC@Poland team.
For more information, please see the Official Announcement.
Other significant primes
47179704131072+1 (GFN):
official announcement pending | Generalized Fermat Prime
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News 
PRPNet September Challenge
Factorial Equinox Challenge
The equinoxes are the only times when the solar terminator (the "edge" between night and day) is perpendicular to the equator. As a result, the northern and southern hemispheres are equally illuminated. The Latinate names vernal equinox (spring) and autumnal equinox (fall) are often used. To celebrate we're running a PRPNet challenge at the FPS (factorial prime search) from 22nd 12:00 UTC until 27th of September 12:00 UTC.
To take part, you have to activate the following line in prpclient.ini:
server=FPS:100:1:prpnet.primegrid.com:12002
Stats will be available at the well known place here.
All previous PRPNet challenge stats can be found here.
Discussion and more information can be found here: 2017 PRPNet September Challenge.
Good luck!
22 Sep 2017 | 13:12:15 UTC
· Comment
Another PPS-Mega Prime!
On 15 September 2017, 11:01:15 UTC, PrimeGrid’s PPS Mega Prime Search project found the Mega Prime:
1127*2^3427219+1
The prime is 1,031,699 digits long and will enter Chris Caldwell's The Largest Known Primes Database ranked 203rd overall.
The discovery was made by Randall Scalise (Randall J. Scalise) of the United States using an Intel(R) Core(TM) i5-4590 CPU @ 3.30GHz with 6GB RAM, running Linux. This computer took about 1 hour 13 minutes to complete the primality test using LLR.
The prime was verified on 15 September 2017, 22:09:16 UTC by Hans-Jürgen Bergelt (Hans-Jürgen Bergelt) of Germany using an Intel(R) Core(TM) i7-3960X CPU @ 3.30GHz with 8GB RAM, running Microsoft Windows 7. This computer took about 1 hour 49 minutes to complete the primality test using LLR. Hans-Jürgen is a member of the SETI.Germany team.
For more details, please see the official announcement.
16 Sep 2017 | 10:23:50 UTC
· Comment
We Need Your Help!
In the past, donations were nice to have, but not critical to our operation. As you likely already know, RackSpace is ending our free hosting. While all of the PrimeGrid admins volunteer their effort, equipment, and electricity, as do all of its members, PrimeGrid needs to find and afford a home.
In choosing a path forward, we have considered both current and ongoing costs, as well as maintaining quality of service at the levels to which we've become accustomed. In doing so, the best option for PrimeGrid is to purchase servers and house them at a paid colocation service.
Moving forward, PrimeGrid needs to cover the 3,500 euro cost of the initial hardware purchase, and then needs to start covering the costs of colocation. Ultimately, we will need to plan for hardware lifecycle as well. We are quite appreciative of the donations we have received towards this effort, and you can see our progress here: https://www.primegrid.com/donations.php where it quickly becomes evident that we still have a ways to go.
Your contributions are greatly appreciated and will help keep PrimeGrid strong and viable in the years ahead. We have done a lot of great work here, and hope to ensure its continued success.
15 Sep 2017 | 20:40:28 UTC
· Comment
AP26 Found!
On 5 September 2017, 08:23:41 UTC, PrimeGrid’s AP27 Search (Arithmetic Progression of 27 primes) found the progression of 26 primes:
48277590120607451+37835074*23#*n for n=0..25
It is the 7th known AP26 known to exist, and the fourth found at PrimeGrid.
The discovery was made by Bruce E. Slade (Renix1943) of the United States using a NVIDIA GTX 970 GPU in an Intel(R) Core(TM) i3-6100 @ 3.70GHz CPU with 16GB RAM, running Microsoft Windows 10 Core Edition. This computer took about 41 minutes to process the task (each task tests 100 progression differences of 10 shifts each). Bruce is a member of the Aggie The Pew team.
The progression was verified on 5 September 2017 19:34:24 UTC, by Axel Schneider (axels) of Germany using an NVIDIA GTX 680 GPU on an Intel(R) Core(TM)2 Quad Q9400 CPU @ 2.66GHz with 8GB RAM running Microsoft Windows 7 Home Premium Edition. This computer took about 2 hours 6 minutes to process the task. Axel is a member of the SETI.Germany team.
For more details, please see the official announcement.
7 Sep 2017 | 16:51:26 UTC
· Comment
GFN-1048576 Mega Prime!
On 29 August 2017, 14:15:23 UTC, PrimeGrid’s Generalized Fermat Prime Search found the Generalized Fermat mega prime:
919444^1048576+1
The prime is 6,253,210 digits long and enters Chris Caldwell's The Largest Known Primes Database ranked 1st for Generalized Fermat primes and 12th overall. This is the first Generalized Fermat prime found for n=20, the second-largest prime found by PrimeGrid, and the second-largest non-Mersenne prime.
The discovery was made by Sylvanus A. Zimmerman (Van Zimmerman) of the United States using a Nvidia GeForce GTX 1060 in an Intel(R) Xeon(R) E3-1225 v3 CPU at 3.20GHz with 8GB RAM, running Microsoft Windows 10 Professional Edition. This GPU took about 4 hours 43 minutes to probable prime (PRP) test with GeneferOCL4. Sylvanus is a member of the Aggie The Pew team.
Double-checker information will be announced once available.
The PRP was confirmed prime by an Intel(R) Core(TM) i7-7700K CPU @ 4.20GHz with 16GB RAM, running Microsoft Windows 10 Professional Edition. This computer took about 3 days, 23 hours, 53 minutes to complete the primality test using multithreaded LLR.
For more details, please see the official announcement.
2 Sep 2017 | 17:03:28 UTC
· Comment
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News is available as an RSS feed 
Newly reported primes2375*2^1457811+1 (composite); 9195*2^1457794+1 (ext2097); 3727652988237*2^1290000-1 (usverg); 3725634193125*2^1290000-1 (RussellBest); 5407*2^1457678+1 (RGB); 59909644^32768+1 ([BOINC@Poland]mimeq); 59850740^32768+1 (NUCCpod_NAPTIMELABS_01); 59858148^32768+1 (TONYHongKong); 3720815370627*2^1290000-1 (KWSN-SpongeBob SquarePants); 3720800327307*2^1290000-1 (KWSN-SpongeBob SquarePants); 3721745642685*2^1290000-1 (TeeVeeEss); 3720255807765*2^1290000-1 (neuralstatic); 3720299748165*2^1290000-1 (Krzysiak_PL_GDA); 3722645982195*2^1290000-1 (mclknight); 3722496953565*2^1290000-1 (Randall J. Scalise); 8721*2^1457528+1 (Randall J. Scalise); 8565*2^1457449+1 (Charles Jackson); 3723571452645*2^1290000-1 (TeeVeeEss); 3723164887647*2^1290000-1 (pons66); 3719462989305*2^1290000-1 (E. T. Drumm) Last 24 hoursTop participants by work done in the last 24 hours | Top teams by work done in the last 24 hours |
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