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1) Message boards : Generalized Cullen/Woodall prime search : GCW-Sieve is SUSPENDED (Message 117621)
Posted 482 days ago by Reggie

Unless I'm mistaken another BOINC project is already doing the sieving for CRUS.


You're correct; yoyo@home is already doing this sieving.
2) Message boards : AP26 - AP27 Search : List for all APs (Message 116963)
Posted 503 days ago by Reggie
Ok, so is there any reason you're using AP20s? You could use the AP23s at the link I posted. There aren't as many of them, but it should work unless you really need two million primes. This would substantially reduce the server load as you only need to load one page.
3) Message boards : Number crunching : Mathematics Awareness Month Challenge (Message 116961)
Posted 503 days ago by Reggie
WooHoo,

Had a great time, however...

I can no longer run more than 2 CPU tasks at once???

I HAD modified my APP_CONFIG file and changed the BOINC preference to 8.33%, now that the challenge is over I have set BOINC back to 100% and tried deleting the APP_CONFIG and/or changing APP_CONFIG to
<app_config>
<app>
<name>llrESP</name>
<fraction_done_exact/>
<max_concurrent>6</max_concurrent>
</app>
<app_version>
<app_name>llrESP</app_name>
<cmdline>-t 6</cmdline>
<avg_ncpus>6</avg_ncpus>
</app_version>
</app_config>

but all I get is 2 tasks running of the 5 it has downloaded

It's like the APP_CONFIG has persisted

Any thoughts???

Thanx

Dad


Try restarting your BOINC client if you haven't already.
4) Message boards : AP26 - AP27 Search : List for all APs (Message 116948)
Posted 503 days ago by Reggie
I'm still not quite sure WHY you're trying to get everyone's APs. The significant APs (23+) can all be found here. These aren't really all that helpful for generating primes. A better technique would be to use the Sieve of Eratosthenes or something else. Is there any other reason you want the small APs?
5) Message boards : 321 Prime Search : Welcome to the 321 Prime Search (Message 116540)
Posted 514 days ago by Reggie
Welcome to the 321 Prime Search

A 321 (or Thabit) number is in the form of 3*2^n-1. A 321 number of the second kind is in the form 3*2^n+1. Primegrid is searching for primes in both forms. These numbers have been studied by mathematicions since Thābit ibn Qurra in the 9th century.

Originally, 321 primes were being searched for by the 321 Search Project. Primegrid completely took over the search in 2008.

Further reading:
List of Ns for which 3*2^n-1 is prime
List of Ns for which 3*2^n+1 is prime
Thabit Number on Wikipedia

Primes found at Primegrid:
3*2^11895718-1
3*2^11731850-1
3*2^11484018-1
3*2^10829346+1
3*2^7033641+1
3*2^6090515-1
3*2^5082306+1
3*2^4235414-1
3*2^2291610+1
6) Message boards : Cullen/Woodall prime search : Welcome to the Cullen/Woodall Prime Search (Message 116530)
Posted 514 days ago by Reggie
Welcome to the Cullen/Woodall Prime Search

A Cullen number in the form of n*2^n+1. Fr. James Cullen first studied these numbers in 1905 because they have interesting divisibility properties. It is conjectured that there are infinitely many n values that will yield Cullen primes, though it has been shown that almost all are composite.

Further reading:
Cullen Number on Wikipedia
Top Twenty Cullen Primes in Chris Caldwell's Database

The following n values yield prime Cullen numbers (OEIS A005849) (ones found at Primegrid highlighted):

1, 141, 4713, 5795, 6611, 18496, 32292, 32469, 59656, 90825, 262419, 361275, 481899, 1354828, 6328548, and 6679881.

A Woodall number is in the form n*2^n-1. They are named after Herbert J. Woodall in 1917, when he studied them and their divisibility properties after being inspired by Fr. James Cullen. They are also called Cullen numbers of the second kind. Similarly to Cullen numbers, it is conjectured that there are infinitely many n values that will yield Woodall primes, though it has been shown that almost all are composite.

Further reading:
Woodall Number on Wikipedia
Top Twenty Woodall Primes in Chris Caldwell's Database

The following n values yield prime Woodall numbers (OEIS A002234) (ones found at Primegrid highlighted):

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, 3752948, and 17016602.
7) Message boards : Number crunching : Badges III (Message 116195)
Posted 523 days ago by Reggie
8) Message boards : Number crunching : unfair? credit distribution??? (Message 116037)
Posted 527 days ago by Reggie
I don't know a lot about the credit ratios, but to start out with, 321 has a 10% long job bonus that GFN-18 doesn't, so that accounts for some of it, but nowhere close to all (after accounting for this bonus, 321 makes almost exactly 5x more from the numbers you gave). I also know that the GFN projects are extremely more focused on GPUs, so you would probably be better off using your CPU on a CPU only project.

I know Mike Goetz works really hard on equalizing credit ratios, but I believe he mainly focuses on keeping the different LLR amounts consistant. I don't know how he compares the GFN and LLR projects, or the sieving ones.

Also, your credits per minute are messed up. Using your numbers, I got .044credit/sec on 321 before removing the long job bonus, and .008credit/sec on GFN-18.
9) Message boards : Number crunching : NVIDIA-GFN taking 100% of one CPU as well as GPU (Message 115585)
Posted 543 days ago by Reggie
See this thread.
10) Message boards : Number crunching : Badges II (Message 114000)
Posted 570 days ago by Reggie


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