Welcome to the Olympics Challenge

The Olympic Game celebrations

Come join the fun...there's no charge. Participate and compare your scores to others. :) NOTE: Actual start time of Olympics Challenge is 3 Aug 18:00 UTC and will last for 48 hours til 5 Aug 18:00 UTC.

In honor of the Olympics, PrimeGrid is offering a 48 hour Challenge on The Riesel Problem (Sieve).

To participate in the Challenge, please select only the TRP (Sieve) project in your PrimeGrid preferences section. The Challenge will begin 3 Aug 2012 18:00 UTC and end 5 Aug 2012 18:00 UTC. Application builds are available for MacIntel, Linux 32 & 64 bit and Windows 32 & 64 bit.
Note: 64 bit builds benefit from a 1.7X speed advantage over 32 bit...so 1.7X the credit. :)


NOTE: In your PrimeGrid preferences section, set "Send work from any subproject if selected projects have no work" to no to guarantee that no other work will be sent.

Recommendation: The TRP (Sieve) application requires a one time download of a 32.4MB sieve file. Please consider running a few TRP (Sieve) WU's before the Challenge begins so your client will already have the sieve file. This way, bandwidth can be used to deliver WU's instead of the sieve file. :) Thank you!


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 3 Aug 2012 18:00 UTC and received BEFORE 5 Aug 2012 18:00 UTC will be considered for credit. Since this is a fixed credit project, we'll be using cobblestones for scoring.

About the Olympics
After a 1501 year pause the modern Olympic games were reinvigorated by the founding of the International Olympic Committee in 1894 by Pierre de Coubertin. In the 118 years since the reboot of the Olympics many events have been added and removed, like e.g. writing poetry, painting, golf and rugby. No matter the sport an athlete participates in, it is the Olympic spirit that should prevail: the competition should be fair and friendly. To commemorate the current Summer Olympics taking place in London (United Kingdom), PrimeGrid offers this challenge in the hope that as per usual the Olympic spirit will also prevail here.
For more information on the Olympics see Wikipedia or the IOC website

About The Riesel Problem

Hans Ivar Riesel (born 1929 in Stockholm) is a Swedish mathematician. In 1956, he showed that there are an infinite number of positive odd integer k's such that k*2^n-1 is composite (not prime) for every integer n>=1. These numbers are now called Riesel numbers. He further showed that k=509203 was such one.

It is conjectured that 509203 is the smallest Riesel number. The Riesel problem consists in determining that 509203 is the smallest Riesel number. To show that it is the smallest, a prime of the form k*2^n-1 must be found for each of the positive integer k's less than 509203. As of June 2012, there remain 55 k's for which no primes have been found. They are as follows:

2293, 9221, 23669, 31859, 38473, 40597, 46663, 67117, 74699, 81041, 93839, 97139, 107347, 121889, 129007, 143047, 146561, 161669, 192971, 206039, 206231, 215443, 226153, 234343, 245561, 250027, 273809, 304207, 315929, 319511, 324011, 325123, 327671, 336839, 342847, 344759, 362609, 363343, 364903, 365159, 368411, 371893, 384539, 386801, 397027, 398023, 402539, 409753, 444637, 470173, 474491, 477583, 485557, 494743, 502573

For a more detailed history and status of the Riesel problem, please visit Wilfrid Keller's The Riesel Problem: Definition and Status.

Additional Information


Riesel Number (Wolfram MathWorld)
Riesel Number (Wiki)
Riesel Number (The Prime Glossary)


The Riesel problem is to k*2^n-1 as the Sierpinski problem is to k*2^n+1. There is no equivalent to the 'prime' Sierpinski problem since k=509203, the conjectured smallest Riesel number, is prime.

What is sieving?

Sieving is the first step to prime finding. In general, a sieve separates wanted/desired elements from unwanted material using a tool such as a mesh, net or other filtration or distillation methods. The word "sift" derives from this term. (Wikipedia - Sieve)

In PrimeGrid's case, the desired elements ultimately are prime numbers and the unwanted material are composite numbers. Our tool of choice for PSP/SoB sieve is Geoff Reynolds' sr2sieve program. It eliminates possible candidates by removing numbers that have small factors. As this process is much faster than primality testing, it is good to thoroughly sieve a data set before primality testing.

Sieving removes many candidates at the beginning. However, the deeper the sieve goes, the slower the rate of removal, till eventually sieving removes candidates at the same rate as primality testing. This is sometimes referred to as "optimal depth". Primality testing is recommended at this point.

There are many factors that determine how much time and how deep to sieve. After sieving, all the remaining candidates must be primality tested to determine their "prime" status.

32 bit OS with 64 bit CPU

This is for those who are "driving with the hand brake active" (running a 32 bit OS on a 64 bit machine) ;) Wubi is a very nice tool that installs Ubuntu as a dual boot to your 64 bit machine. It's as simple as adding a program to Windows. You can even uninstall it like you would any other program. :)

Wubi - Ubuntu Installer

After getting 64 bit OS running on your machine, here's a link to ALL BOINC clients (including Linux x64): http://boinc.berkeley.edu/download_all.php If you are new to Linux and need help getting set up, let us know.

It really is simple. :) With that said, check what installations WUBI will NOT work on: Unsupported set-ups

Ubuntu has a power save feature that throttles the CPU frequency down to save power. It does not treat BOINC as an active program so will throttle down thus causing under-performance. For those downloading the latest Ubuntu 10.04 (http://www.ubuntu.com/), please follow these directions to make sure the frequency is not throttled down while BOINC is running:

1. In Ubuntu, right click the top menu bar
2. Select add to panel
3. Select "CPU Frequency Scaling Monitor"
4. Click add

This will add a processor icon to the top menu. Click on the icon and set to "Performance". This also allows you to see the CPU frequency.

Welcome to the Olympics Challenge

The Olympic Game celebrations

Come join the fun and register...there's no charge. Participate and compare your scores to others. :) NOTE: Actual start time of Olympics Challenge is 3 Aug 18:00 UTC and will last for 48 hours til 5 Aug 18:00 UTC.

In honor of the Olympics, PrimeGrid is offering a 48 hour Challenge on The Riesel Problem (Sieve).

To participate in the Challenge, please select only the TRP (Sieve) project in your PrimeGrid preferences section. The Challenge will begin 3 Aug 2012 18:00 UTC and end 5 Aug 2012 18:00 UTC. Application builds are available for MacIntel, Linux 32 & 64 bit and Windows 32 & 64 bit.
Note: 64 bit builds benefit from a 1.7X speed advantage over 32 bit...so 1.7X the credit. :)


NOTE: In your PrimeGrid preferences section, set "Send work from any subproject if selected projects have no work" to no to guarantee that no other work will be sent.

Recommendation: The TRP (Sieve) application requires a one time download of a 32.4MB sieve file. Please consider running a few TRP (Sieve) WU's before the Challenge begins so your client will already have the sieve file. This way, bandwidth can be used to deliver WU's instead of the sieve file. :) Thank you!


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 3 Aug 2012 18:00 UTC and received BEFORE 5 Aug 2012 18:00 UTC will be considered for credit. Since this is a fixed credit project, we'll be using cobblestones for scoring.

About The Riesel Problem

Hans Ivar Riesel (born 1929 in Stockholm) is a Swedish mathematician. In 1956, he showed that there are an infinite number of positive odd integer k's such that k*2^n-1 is composite (not prime) for every integer n>=1. These numbers are now called Riesel numbers. He further showed that k=509203 was such one.

It is conjectured that 509203 is the smallest Riesel number. The Riesel problem consists in determining that 509203 is the smallest Riesel number. To show that it is the smallest, a prime of the form k*2^n-1 must be found for each of the positive integer k's less than 509203. As of June 2012, there remain 55 k's for which no primes have been found. They are as follows:

2293, 9221, 23669, 31859, 38473, 40597, 46663, 67117, 74699, 81041, 93839, 97139, 107347, 121889, 129007, 143047, 146561, 161669, 192971, 206039, 206231, 215443, 226153, 234343, 245561, 250027, 273809, 304207, 315929, 319511, 324011, 325123, 327671, 336839, 342847, 344759, 362609, 363343, 364903, 365159, 368411, 371893, 384539, 386801, 397027, 398023, 402539, 409753, 444637, 470173, 474491, 477583, 485557, 494743, 502573

For a more detailed history and status of the Riesel problem, please visit Wilfrid Keller's The Riesel Problem: Definition and Status.

Additional Information


Riesel Number (Wolfram MathWorld)
Riesel Number (Wiki)
Riesel Number (The Prime Glossary)


The Riesel problem is to k*2^n-1 as the Sierpinski problem is to k*2^n+1. There is no equivalent to the 'prime' Sierpinski problem since k=509203, the conjectured smallest Riesel number, is prime.

What is sieving?

Sieving is the first step to prime finding. In general, a sieve separates wanted/desired elements from unwanted material using a tool such as a mesh, net or other filtration or distillation methods. The word "sift" derives from this term. (Wikipedia - Sieve)

In PrimeGrid's case, the desired elements ultimately are prime numbers and the unwanted material are composite numbers. Our tool of choice for PSP/SoB sieve is Geoff Reynolds' sr2sieve program. It eliminates possible candidates by removing numbers that have small factors. As this process is much faster than primality testing, it is good to thoroughly sieve a data set before primality testing.

Sieving removes many candidates at the beginning. However, the deeper the sieve goes, the slower the rate of removal, till eventually sieving removes candidates at the same rate as primality testing. This is sometimes referred to as "optimal depth". Primality testing is recommended at this point.

There are many factors that determine how much time and how deep to sieve. After sieving, all the remaining candidates must be primality tested to determine their "prime" status.

32 bit OS with 64 bit CPU

This is for those who are "driving with the hand brake active" (running a 32 bit OS on a 64 bit machine) ;) Wubi is a very nice tool that installs Ubuntu as a dual boot to your 64 bit machine. It's as simple as adding a program to Windows. You can even uninstall it like you would any other program. :)

Wubi - Ubuntu Installer

After getting 64 bit OS running on your machine, here's a link to ALL BOINC clients (including Linux x64): http://boinc.berkeley.edu/download_all.php If you are new to Linux and need help getting set up, let us know.

It really is simple. :) With that said, check what installations WUBI will NOT work on: Unsupported set-ups

Ubuntu has a power save feature that throttles the CPU frequency down to save power. It does not treat BOINC as an active program so will throttle down thus causing under-performance. For those downloading the latest Ubuntu 10.04 (http://www.ubuntu.com/), please follow these directions to make sure the frequency is not throttled down while BOINC is running:

1. In Ubuntu, right click the top menu bar
2. Select add to panel
3. Select "CPU Frequency Scaling Monitor"
4. Click add

This will add a processor icon to the top menu. Click on the icon and set to "Performance". This also allows you to see the CPU frequency.

Editorial note
Thanks to all the people that posted but whose posts have now magically disappeared ;) As all your remarks should be resolved now and this post needs to be at the top I have hidden your posts.
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PrimeGrid Challenge Overall standings --- Last update: From Pi to Paddy (2016)

Unless I'm thoroughly mistaking, I should have fixed all concerns that have been voiced above for which I have the buttons.
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PrimeGrid Challenge Overall standings --- Last update: From Pi to Paddy (2016)

No, the only registering you need to do is being signed up with PrimeGrid in general. Which you are. Else you couldn't post here ;) And of course you need to select the correct subproject, which is TRP sieve.
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PrimeGrid Challenge Overall standings --- Last update: From Pi to Paddy (2016)

As stated in first post

"Come join the fun and register...there's no charge"

Do I need to register for this?

Server clock seems to be about 5 minutes fast.
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Server clock seems to be about 5 minutes fast.

Hello,

i don't receive any workunits, but the settings are right :(

woot! all rubies for everything still in the running, at long last :)

woot! all rubies for everything still in the running, at long last :)

(Is it "Gene fer" or "Jennifer"?)

Sorry, I meant to respond to the pronunciation question but must have forgotten.

I concur with Iain's response; it's short for "GENEralized FERmat", so I would pronounce it "Jennifer".

On the other hand, if your wife is the jealous type, it might be safer to pronounce it "jean-fer". :)
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Please do not PM me with support questions. Ask on the forums instead. Thank you!

My lucky number is 75898⁵²⁴²⁸⁸+1

so what's the results of this mass sieving? )

any further progress??
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wbr, Me. Dead J. Dona

Yes, I would also like to know what range was completed during the challenge and how many factors were found.
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Do we have stats yet on how many work units were completed in the challenge, how much was sieved, and how many factors were found?
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Unstickied the thread as the challenge is over and the standings are final. See you all at the next challenge!:

An Apple a Day - October 5th 18:00 UTC
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PrimeGrid Challenge Overall standings --- Last update: From Pi to Paddy (2016)

Do we have stats yet on how many work units were completed in the challenge, how much was sieved, and how many factors were found?
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Disclaimer: numbers are based on best guesses available on current stats, not on actual factual database content.

In total 72266 tasks have been given credit. As on rare occasions I have seen a sieve being double checked, I'm not entirely certain if this is the actual number of tasks done. However if we assume it is, we should have identified between 8200 and 8300 factors (based on my own current find rate of 0.1145/task).
Using the number of tasks given credit, one can also conclude that since each task spans a range of 10G we have sieved a range of 722,66T.
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PrimeGrid Challenge Overall standings --- Last update: From Pi to Paddy (2016)