Please visit donation page to help the project cover running costs for this month

Toggle Menu

Join PrimeGrid

Returning Participants


Leader Boards



1) Message boards : Number crunching : Lennart Vogel Honorary Challenge (Message 131337)
Posted 7 hours ago by Profile Roger
From August 3rd 00:00:00 UTC until August 10th 00:00:00 UTC we will be having a special 7 day challenge running the Extended Sierpinski Problem (ESP) (LLR) to honour Lennart Vogel and his enormous contributions to Primegrid.

More information coming soon!

Until then, here's the links to 2019's completed challenges:

Conjunction of Venus & Jupiter Challenge
Year of the Pig Challenge
Hans Ivar Riesel's 90th Birthday Challenge
50th Anniversary of the Moon Landing Challenge
2) Message boards : Aggie The Pew message board (Message 131256)
Posted 1 day ago by Profile Roger
Hi Nick, welcome to the best team there is.
3) Message boards : Aggie The Pew message board (Message 131255)
Posted 1 day ago by Profile Roger
Nice! Top Gun 2 trailer just dropped:
4) Message boards : Number crunching : 50th Anniversary of the Moon Landing Challenge (Message 131171)
Posted 4 days ago by Profile Roger
Apollo 11 reached the Moon's surface 50 years ago with Neil Armstrong and his fellow astronauts Buzz Aldrin and Michael Collins on board. Here are some key quotes from the mission that put the first people on the Moon.

"I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to the Earth." President John F. Kennedy announces his intention to put a man on the Moon before a joint session of Congress on May 25 1961

"No nation which expects to be the leader of other nations can expect to stay behind in this race for space...We choose to go to the Moon in this decade and do the other things, not because they are easy, but because they are hard." John F. Kennedy explains his lunar ambitions in a speech at Rice University on September 12, 1962

"10, 9, ignition sequence start, 6, 5, 4, 3, 2, 1, zero. All engines running. Liftoff! We have a liftoff! Thirty-two minutes past the hour. Liftoff on Apollo 11!'" Jack King, Nasa Chief of Public Information, commentates on the launch of the Apollo 11 over a live television broadcast on July 16, 1969

"Houston, Tranquility Base here. The Eagle has landed." Neil Armstrong tells Nasa's Mission Control base in Texas that the Eagle landing module has reached the Moon's surface on July 20, 1969

"Roger, Twank...Tranquility, we copy you on the ground. You got a bunch of guys about to turn blue here. We're breathing again. Thanks a lot!" Capsule Commander Charles Duke expresses the relief of Mission Control after nerves were tested during an unexpectedly complicated descent to the Moon

"This is the LM pilot. I'd like to take this opportunity to ask every person listening in, whoever and wherever they may be, to pause for a moment and contemplate the events of the past few hours and to give thanks in his or her own way." Buzz Aldrin's broadcast, shortly after landing on the Moon and before he took a private communion on board the Eagle landing module

"That's one small step for man, a giant leap for mankind." Neil Armstrong fluffs his lines as he steps out of the Eagle landing craft and onto the Moon's surface, turning Nasa's carefully prepared landing script into the most famous tautology of all time

"The surface is fine and powdery. I can kick it up loosely with my toe. It does adhere in fine layers, like powdered charcoal, to the sole and sides of my boots." Neil Armstrong describes the surface of the Moon

"Magnificent desolation" Buzz Aldrin reflects on the view from the Moon after stepping off the Eagle landing module onto the lunar surface

"Hello Neil and Buzz. I'm talking to you by telephone from the Oval room at the White House, and this certainly has to be the most historic telephone call ever made. I just cannot tell you how proud we all are of what you have done. For every American, this has to be the proudest day of their lives." President Richard Nixon congratulates the astronauts on being the first men to walk on the Moon

"Fate has ordained that the men who went to the Moon to explore in peace will stay on the moon to rest in peace. These brave men, Neil Armstrong and Edwin [Buzz] Aldrin, know that there is no hope for their recovery. But they also know that there is hope for mankind in their sacrifice." The opening lines of a speech, prepared by President Nixon's speechwriter William Safire, to be used in the event of a disaster that would maroon the astronauts on the Moon.

"Here Men From The Planet Earth First Set Foot Upon the Moon, July 1969 A.D. We Came in Peace For All Mankind." The inscription on a plaque left behind on the surface of the Moon after the astronauts departed.

We would like to give special thanks to all those Americans who built the spacecraft; who did the construction, design, the tests, and put their hearts and all their abilities into those craft. To those people tonight, we give a special thank you, and to all the other people that are listening and watching tonight, God bless you. Good night from Apollo 11." Neil Armstrong concludes the final television broadcast from Apollo 11 on the night before splashdown, July 23, 1969

“This is the greatest week in the history of the world since Creation.” President Nixon enthuses upon greeting the Apollo 11 crew after they splash down in the Pacific Ocean on Jul 24 1969

"Hey, we missed the whole thing." Buzz Aldrin to Neil Armstrong after watching a video of the press coverage of the Moon landing while in quarantine after splashdown.
5) Message boards : News : 50th Anniversary of the Moon Landing Challenge starts July 15th 20:17 UTC (Message 131104)
Posted 5 days ago by Profile Roger
"Thirty seconds and counting. Astronauts report it feels good. T-25 seconds. Twenty seconds and counting. T-15 seconds, guidance is internal. 12, 11, 10, 9 ... ignition sequence start ... 6, 5, 4, 3, 2, 1, 0 ... All engines running. Liftoff! We have a liftoff ... 32 minutes past the hour, liftoff on Apollo 11!"

To celebrate the 50th Anniversary of humans landing on the Moon, PrimeGrid is running a 5 day challenge from July 15th 2019, 20:17 UTC until July 20th, 20:17 UTC.

Work units from the PPS (LLR) project, which are downloaded and completed during the challenge will count towards your challenge score. Many primes are expected to be found.

For more information and discussion, please see the official challenge thread:
6) Message boards : Number crunching : 50th Anniversary of the Moon Landing Challenge (Message 130784)
Posted 21 days ago by Profile Roger
Welcome to the 50th Anniversary of the Moon Landing Challenge

The fourth Challenge of the 2019 Challenge series is a 5 day challenge to celebrate the 50th Anniversary of the first humans landing on the Moon as part of NASA's Apollo 11 lunar mission. The challenge is being offered on the Proth Prime Search (LLR) application.

On 20 July 1969 an estimated 600 million people, a sixth of the earths population at the time, watched on television as the first humans walked on the Moon. During the Apollo program of the 1960s and '70s, NASA sent nine missions to the Moon. Six of them landed astronauts safely on the surface, the only times humans have visited another world.

Apollo 11 was launched by a Saturn V rocket from Kennedy Space Center on Merritt Island, Florida, on July 16 at 13:32 UTC, and was the fifth crewed mission of NASA's Apollo program. After being sent to the Moon by the Saturn V's third stage, the astronauts separated the spacecraft from it and traveled for three days until they entered lunar orbit. Armstrong and Aldrin then moved into Eagle and landed in the Sea of Tranquillity. Commander Neil Armstrong and lunar module pilot Buzz Aldrin landed the Apollo Lunar Module Eagle on July 20, 1969, at 20:17 UTC. Armstrong became the first person to step onto the lunar surface six hours later on July 21 at 02:56:15 UTC; Aldrin joined him 19 minutes later. They spent about two and a quarter hours together outside the spacecraft, and collected 47.5 pounds (21.5 kg) of lunar material to bring back to Earth. Command module pilot Michael Collins flew the command module Columbia alone in lunar orbit while they were on the Moon's surface. Armstrong and Aldrin spent 21.5 hours on the lunar surface before rejoining Columbia in lunar orbit. They jettisoned Eagle before they performed the maneuvers that propelled the ship out of the last of its 30 lunar orbits on a trajectory back to Earth. They returned to Earth and splashed down in the Pacific Ocean on July 24 after more than eight days in space.

To celebrate the 50th anniversary United States Mint has released the Apollo 11 Fiftieth Anniversary commemorative coins (I actually have one of these) and a documentary film, Apollo 11, with restored footage of the 1969 event, premiered on IMAX in March 2019.

To participate in the Challenge, please select only the Proth Prime Search LLR (PPS) project in your PrimeGrid preferences section. The challenge will begin 15th July 2019 20:17 UTC and end at 20th July 2019 20:17 UTC. Note that PPSE, PPS Mega and PPS-Sieve do not count towards this challenge.

Application builds are available for Linux 32 and 64 bit, Windows 32 and 64 bit and MacIntel. Intel CPUs with FMA3 capabilities (Haswell, Broadwell, Skylake, Kaby Lake, Coffee Lake) will have a very large advantage, and Intel CPUs with AVX-512 (certain recent Intel Skylake-X and Xeon CPUs) will be the fastest.

ATTENTION: The primality program LLR is CPU intensive; so, it is vital to have a stable system with good cooling. It does not tolerate "even the slightest of errors." Please see this post for more details on how you can "stress test" your computer. Tasks on one CPU core will take 1 hour on a fast/newer computers and 4 hours on slower/older computers. If your computer is highly overclocked, please consider "stress testing" it. Sieving is an excellent alternative for computers that are not able to LLR. :)

Highly overclocked Haswell, Broadwell, Skylake, Kaby Lake or Coffee Lake (i.e., Intel Core i7, i5, and i3 -4xxx or better) computers running the application will see fastest times. Note that PPS is running the latest AVX-512 version of LLR which takes full advantage of the features of these newer CPUs. It's faster than the previous LLR app and draws more power and produces more heat. If you have certain recent Intel Skylake-X and Xeon CPUs, especially if it's overclocked or has overclocked memory, and haven't run the new AVX-512 LLR before, we strongly suggest running it before the challenge while you are monitoring the temperatures.

Please, please, please make sure your machines are up to the task.

Time zone converter:

The World Clock - Time Zone Converter

NOTE: The countdown clock on the front page uses the host computer time. Therefore, if your computer time is off, so will the countdown clock. For precise timing, use the UTC Time in the data section at the very top, above the countdown clock.

Scoring Information

Scores will be kept for individuals and teams. Only tasks issued AFTER 15th July 2019 20:17 UTC and received BEFORE 20th July 2019 20:17 UTC will be considered for credit. We will be using the same scoring method as we currently use for BOINC credits. A quorum of 2 is NOT needed to award Challenge score - i.e. no double checker. Therefore, each returned result will earn a Challenge score. Please note that if the result is eventually declared invalid, the score will be removed.

At the Conclusion of the Challenge
    We kindly ask users "moving on" to ABORT their tasks instead of DETACHING, RESETTING, or PAUSING.

    ABORTING tasks allows them to be recycled immediately; thus a much faster "clean up" to the end of an LLR Challenge. DETACHING, RESETTING, and PAUSING tasks causes them to remain in limbo until they EXPIRE. Therefore, we must wait until tasks expire to send them out to be completed.

    Please consider either completing what's in the queue or ABORTING them. Thank you. :)

About the Proth Prime Search

The Proth Prime Search is done in collaboration with the Proth Search project. This search looks for primes in the form k*2^n+1. With the condition 2^n > k, these are often called Proth primes. This project also has the added bonus of possibly finding factors of "classical" Fermat numbers or Generalized Fermat numbers. As this requires PrimeFormGW (PFGW) (a primality-testing program), once PrimeGrid finds a prime, it is then tested on PrimeGrid's servers for divisibility.

Proth Search only searches for k<1200. PrimeGrid created an extension to that which includes all candidates 1200<k<10000 for n<5M. It is this extension which we call PPSE.

Initially, PrimeGrid's PPS project's goal was to double check all previous work up to n=500K for odd k<1200 and to fill in any gaps that were missed. We have accomplished that now and have increased it to n=3M. PG's LLRNet searched up to n=200,000 and found several missed primes in previously searched ranges. Although primes that small did not make it into the Top 5000 Primes database, the work was still important as it may have led to new factors for "classical" Fermat numbers or Generalized Fermat numbers. While there are many GFN factors, currently there are only 297 "classical" Fermat number factors known. Current primes found in PPS definitely make it into the Top 5000 Primes database.

For more information about "Proth" primes, please visit these links:

About Proth Search

The Proth Search project was established in 1998 by Ray Ballinger and Wilfrid Keller to coordinate a distributed effort to find Proth primes (primes of the form k*2^n+1) for k < 300. Ray was interested in finding primes while Wilfrid was interested in finding divisors of Fermat number. Since that time it has expanded to include k < 1200. Mark Rodenkirch (aka rogue) has been helping Ray keep the website up to date for the past few years.

Early in 2008, PrimeGrid and Proth Search teamed up to provide a software managed distributed effort to the search. Although it might appear that PrimeGrid is duplicating some of the Proth Search effort by re-doing some ranges, few ranges on Proth Search were ever double-checked. This has resulted in PrimeGrid finding primes that were missed by previous searchers. By the end of 2008, all new primes found by PrimeGrid were eligible for inclusion in Chris Caldwell's Prime Pages Top 5000. Sometime in 2009, over 90% of the tests handed out by PrimeGrid were numbers that had never been tested.

PrimeGrid intends to continue the search indefinitely for Proth primes.

What is LLR?

The Lucas-Lehmer-Riesel (LLR) test is a primality test for numbers of the form N = k*2^n − 1, with 2^n > k. Also, LLR is a program developed by Jean Penne that can run the LLR-tests. It includes the Proth test to perform +1 tests and PRP to test non base 2 numbers. See also:

(Edouard Lucas: 1842-1891, Derrick H. Lehmer: 1905-1991, Hans Riesel: 1929-2014).

7) Message boards : Number crunching : Badges III (Message 130751)
Posted 22 days ago by Profile Roger
3,2,1, blastoff!

8) Message boards : Number crunching : Hans Ivar Riesel's 90th Birthday Challenge (Message 130539)
Posted 30 days ago by Profile Roger
The results are final!

Top 3 individuals:

1: zunewantan
2: Scott Brown
3: DeleteNull

Top 3 teams:

1: Czech National Team
2: Aggie The Pew
3: SETI.Germany

Congratulations to the winners, and well done to everyone who participated.
See you at the 50th Anniversary of the Moon Landing Challenge!
9) Message boards : General discussion : possibility of finding a prime (Message 130432)
Posted 35 days ago by Profile Roger
Some of the sub-projects have chance of prime discussions:
321 Prime Search
Prime Sierpinski Problem
The Riesel Problem
Sierpinski/Riesel Base 5 Problem
Generalized Fermat Prime Search

If you could find out the number of tasks in a range you can calculate the possibility (average 1 in x tasks) of finding a prime.
10) Message boards : Prime Sierpinski Problem : Chance of PSP Prime (Message 130431)
Posted 35 days ago by Profile Roger
93.36% is chanse of no prime.

If I did not make any mistake the chanse of 2 or more primes is 37.53%

First part is correct.
1 - 0.0664 = 0.9336 which is the chance no prime is found 20-21M, i.e. 93.36%.

There is a chance of 0,1,2,3,4,5,6 or 7 primes. Mostly we are interested in the chance of finding a prime, as opposed to no prime, which includes finding 1-7 primes. Using the percentages in the last column of the table for the whole range 20-50M I calculated:
Chance of no prime: 23.09%
Chance of 1 prime: 39.14%
Chance of 2 primes: 26.43%
Chance of 3 primes: 9.280%
Chance of 4 primes: 1.835%
Chance of 5 primes: 0.2045%
Chance of 6 primes: 0.01190%
Chance of 7 primes: 0.000280%

To calculate the chances you have to go through all the combinations of prime/no-prime, which gets hard at 3 primes, luckily you can just swap the prime/no-prime percentages to calculate for 4 primes. The number of combination formula, or the number of ways to combine k items from a set of n is n! / (n-k)!k!
It's useful to calculate the number of combinations, it saved me making a mistake.

Next 10 posts
[Return to PrimeGrid main page]
Copyright © 2005 - 2019 Rytis Slatkevičius (contact) and PrimeGrid community. Server load 1.18, 1.28, 1.44
Generated 21 Jul 2019 | 9:53:08 UTC