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1)
Message boards :
Number crunching :
Summer Solstice Challenge
(Message 96814)
Posted 2441 days ago by [DPC]Charley
With the cleanup done and stats updated, we can announce the top participants and teams.
Congratulations go to:
1 zunewantan
2 Scott Brown
3 tng*
And in the teams department we can find these at the top:
1 Aggie The Pew
2 Czech National Team
3 Sicituradastra.
Thanks for all the participation and hope to see you during the next challenge!

2)
Message boards :
News :
Summer Solstice Challenge starts 20 June 2016 22:34 UTC
(Message 95800)
Posted 2470 days ago by [DPC]Charley
The longest day of the year is drawing near and to mark this turning point in the year, PrimeGrid is offering a 5 day challenge on Proth MEGA Prime Search (LLR). Only PPS MEGA is part of the challenge!
For more information, questions and general banter and merry making please join us on the forums

3)
Message boards :
Number crunching :
Summer Solstice Challenge
(Message 95799)
Posted 2470 days ago by [DPC]Charley
Welcome to Summer Solstice Challenge
The longest day of the year is drawing near and to mark this turning point in the year, PrimeGrid is offering a 5 day challenge on Proth MEGA Prime Search (LLR). Only PPS MEGA is part of the challenge!
To participate in the Challenge, please select only the Proth MEGA Prime Search (LLR) project in your PrimeGrid preferences section. The challenge will begin 20 June 2016 22:34 UTC and end 25 June 2016 22:34 UTC. Application builds are available for Linux , Windows and MacIntel 32 bit and 64 bit. CPU's with AVX capabilities will be significantly faster than the ones without, as this instruction set allows for more computing power.
Please note the atypical start and stop times of this challenge!
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. WU's will take just under 2 hours on the fastest/newest computers and 3(+) 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 (i.e., Intel Core i7, i5, and i3 4xxx) computers running the application will see fastest times. Note that PPS is now running the latest, brand new FMA3 version of LLR which takes full advantage of the new Haswell features. It's faster than the previous LLR app and draws more power and produces more heat. The new FMA3 LLR app is version 6.24. If you have a Haswell CPU, especially if it's overclocked or has overclocked memory, and haven't run the new FMA3 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 to the left of the countdown clock.
Scoring Information
Scores will be kept for individuals and teams. Only work units issued AFTER 20 June 2016 22:34 UTC and received BEFORE 23 April 2014 2014 16:16 UTC will be considered for credit. We will use the same scoring method as for BOINC credit. The only difference is that the primary and double checker of a WU will receive the same score.
Therefore, each completed WU will earn a unique score based on its n value. The higher the n, the higher the score. This is different than BOINC cobblestones! 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.
For details on how the score is calculated, please see this thread.
At the Conclusion of the Challenge
We kindly ask users "moving on" to ABORT their WU's instead of DETACHING, RESETTING, or PAUSING.
ABORTING WU's allows them to be recycled immediately; thus a much faster "clean up" to the end of an LLR Challenge. DETACHING, RESETTING, and PAUSING WU's causes them to remain in limbo until they EXPIRE. Therefore, we must wait until WU's 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 of 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 primalitytesting 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 that the Challenge will be on.
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=2M. 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 293 "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 redoing some ranges, few ranges on Proth Search were ever doublechecked. 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 have never been tested.
PrimeGrid intends to continue the search indefinitely for Proth primes.
What is LLR?
The LucasLehmerRiesel (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 LLRtests. It includes the Proth test to perform +1 tests and PRP to test non base 2 numbers. See also:
(Edouard Lucas: 18421891, Derrick H. Lehmer: 19051991, Hans Riesel: 19292014).

4)
Message boards :
Number crunching :
Makar Sankranti Challenge
(Message 95050)
Posted 2501 days ago by [DPC]Charley
With the final unit validated, we can announce the winners!
The top 3 participants are:
1. Ross*
2. zunewantan
3. Van Zimmerman
The top 3 teams are:
1. Sicituradastra.
2. Aggie The Pew
3. SETI. Germany
The overall stats have also been updated.
Thanks for participating and see you at the next challenge, 2025 June on PPS Mega.

5)
Message boards :
Number crunching :
Cullen Birthday Challenge
(Message 94584)
Posted 2518 days ago by [DPC]Charley
With just about 19 hours to go, it's time for the usual end of challenge reminder:
At the Conclusion of the Challenge
We would prefer users "moving on" to finish those tasks they have downloaded, if not then please ABORT the WU's instead of DETACHING, RESETTING, or PAUSING.
ABORTING WU's allows them to be recycled immediately; thus a much faster "clean up" to the end of a Challenge. DETACHING, RESETTING, and PAUSING WU's causes them to remain in limbo until they EXPIRE. Therefore, we must wait until WU's expire to send them out to be completed.

6)
Message boards :
Number crunching :
From Pi to Paddy Challenge
(Message 94583)
Posted 2518 days ago by [DPC]Charley
TheDawgz have heard back from Charley  he has been and still is swamped at work ("very looooong days")  he will deal with this as soon as possible  but, it will likely not happen until next week sometime.
thanks for the info!
the work is still a significant disruptive factor during free time ;)
Quite. Finally had some time to dive into and fixed it. Thanks for all you patience :)

7)
Message boards :
News :
Cullen Birthday Challenge starts April 19th 2016, 18:00:00 UTC
(Message 94008)
Posted 2536 days ago by [DPC]Charley
To celebrate the 149th birthday of James Cullen, the namesake of the Cullen primes we're looking for at PrimeGrid, we are hosting a 9 day challenge. This challenge starts on April 19th 18:00 UTC, his birthday.
For more information, questions and general banter and merry making please join us on the forums

8)
Message boards :
Number crunching :
Cullen Birthday Challenge
(Message 94007)
Posted 2536 days ago by [DPC]Charley
Welcome to the Cullen Birthday Challenge
The startdate is the 149th birthday of James Cullen, had he still been alive. With this being a a prime birthday, it seems like a very appropriate occasion to celebrate by hosting a challenge. And what projects are better suited in that case than our Cullen and Woodall (Cullen primes of the second kind) projects?
The person we're celebrating is Father James Cullen, born on 19 April 1867 in Ireland. He was a student of Mathematics and Theology.
To participate in the Challenge, please select either the Cullen (LLR) or Woodall (LLR) project in your PrimeGrid preferences section. The challenge will begin April 19th 2016, 18:00:00 UTC and end April 28th 2016, 18:00:00 UTC. Application builds are available for Linux , Windows and MacIntel 32 bit and 64 bit. Intel CPU's with AVX and FMA capabilities will be significantly faster than the ones without, as this instruction set allows for more computing power.
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. WU's will take about 1 to 2 days on very fast/newer computers and 4+ days 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. :)
Restricted airflow is one of the primary reasons for overheating. Take the time to monitor the fans and review the dust buildup. 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 to the left of the countdown clock.
Scoring Information
Scores will be kept for individuals and teams. Only work units issued AFTER April 19th 2016, 18:00:00 UTC and received BEFORE April 28th 2016, 18:00:00 UTC will be considered for credit.
Therefore, each completed WU will earn a unique score based on its n value. The higher the n, the higher the score. This is different than BOINC cobblestones! 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 would prefer users "moving on" to finish those tasks they have downloaded, if not then please ABORT the WU's instead of DETACHING, RESETTING, or PAUSING.
ABORTING WU's allows them to be recycled immediately; thus a much faster "clean up" to the end of an LLR Challenge. DETACHING, RESETTING, and PAUSING WU's causes them to remain in limbo until they EXPIRE. Therefore, we must wait until WU's expire to send them out to be completed.
Please consider either completing what's in the queue or ABORTING them. Thank you. :)
About Woodall Prime Search
Woodall Numbers (sometimes called Cullen numbers 'of the second kind') are positive integers of the form Wn = n*2^n1, where n is also a positive integer greater than zero. Woodall numbers that are prime are called Woodall primes (or Cullen primes of the second kind).
The Woodall numbers Wn are primes for the following n:
2, 3, 6, 30, 75, 81, 115, 123, 249, 362, 384, 462, 512, 751, 822, 5312, 7755, 9531, 12379, 15822, 18885, 22971, 23005, 98726, 143018, 151023, 667071, 1195203, 1268979, 1467763, 2013992, 2367906, and 3752948 and composite for all other n less than 9108979.
It is conjectured that there are infinitely many such primes. Currently, PrimeGrid is testing for Woodall primes in the n=11M  n=12M level (M=mega, 10^6). The last 3 Woodall primes found by PrimeGrid are:
2013992*2^2013992−1 (Lasse Mejling Andersen): official announcement  decimal representation  Prime Pages Entry
2367906*2^2367906−1 (Stephen Kohlman): official announcement  decimal representation  Prime Pages Entry
3752948*2^3752948−1 (Matthew J. Thompson): official announcement  decimal representation  Prime Pages Entry
For more information on Woodall numbers, please visit the following sites:
Cullen Primes
Cullen numbers are a special kind Proth number. They were first studied by James Cullen in 1905 and are of the form n * 2^n + 1.
As of August 2009, the largest known Cullen prime is 6679881 * 2^6679881 + 1. It is a megaprime with 2,010,852 digits and was discovered by a PrimeGrid participant from Japan.
A Cullen number Cn is divisible by p = 2n − 1 if p is a prime number of the form 8k  3; furthermore, it follows from Fermat's little theorem that if p is an odd prime, then p divides Cm(k) for each m(k) = (2k − k) (p − 1) − k (for k > 0). It has also been shown that the prime number p divides C(p + 1) / 2 when the Jacobi symbol (2  p) is −1, and that p divides C(3p − 1) / 2 when the Jacobi symbol (2  p) is +1.
It is unknown whether there exists a prime number p such that Cp is also prime.
What is LLR?
The LucasLehmerRiesel (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 LLRtests. It includes the Proth test to perform +1 tests and PRP to test non base 2 numbers. See also:(Edouard Lucas: 18421891, Derrick H. Lehmer: 19051991, Hans Riesel: born 1929)
Best of Luck!!!

9)
Message boards :
Number crunching :
From Pi to Paddy Challenge
(Message 94005)
Posted 2536 days ago by [DPC]Charley
You are absolutely right. I clicked open the GFN challenge and forgot to change the URL. Previous post will be amended shortly.

10)
Message boards :
Number crunching :
From Pi to Paddy Challenge
(Message 94001)
Posted 2536 days ago by [DPC]Charley
With all the work units that could influence the standings being validated, the winners can be announced for this challenge.
Individuals
1. Scott Brown
2. zunewantan
3. tng*
Teams
1. Aggie The Pew
2. Czech National Team
3. Sicituradastra.
The overall leaderboard has been updated with this challenge.

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