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-   -   prime problem (https://www.mersenneforum.org/showthread.php?t=2427)

wblipp 2004-05-07 04:19

How long does the contest run?

I used all numbers for "a" in my search. I think the impact of composite versus prime would be small. It would tend towards primes at small coefficients because composites would not exclude any new factors. At larger coefficients the composites would often weed out more than one prime, so the advantage probably switches to composite coefficients.

Agrajag 2004-05-08 08:37

[QUOTE=wblipp]How long does the contest run?[/QUOTE]

until the end of semester - so about 4 weeks from now

biwema 2004-05-08 11:25

In this case I recomend you to search primorial twins (sieve using NewPGen, and verify with pfgw) which are larger than the largest one thusfar this year.
If you have such a prime, you can try to beat the 44k bit candidate.

wblipp 2004-05-30 18:28

[QUOTE=Agrajag]until the end of semester - so about 4 weeks from now[/QUOTE]

Is class over? What was your largest oreo, and what was the largest oreo in the class? How were they found?

William

Agrajag 2004-06-01 06:15

it's not quite over, we've got until the 10th
I found an 11287 bit one, but someone has beaten me with a 34522 bit number, which I haven't tried to beat
The number are viewable here:
[url]http://www.it.usyd.edu.au/~dasymond/cookies.html[/url]

thanks a lot for your help! :)

tom11784 2004-06-01 10:15

that's a little larger than the [url]http://www.alpertron.com.ar/ECM.HTM[/url] ecm can handle :sad:

wblipp 2004-06-01 14:15

[QUOTE=Agrajag]it's not quite over, we've got until the 10th
I found an 11287 bit one, but someone has beaten me with a 34522 bit number, [/QUOTE]

Are you feeling lucky? If so, I've got some sieved ranges you could test for much larger oreos.

I started NewPgen on a range that I picked with too little pre-analysis. When I got around to the analysis, the range was too large and the numbers were too large to have much hope of finishing in the time available. I let NewPgen run a couple of weeks - it removed about 84% of the range. With unlimited time it should be sieved more, but with a fixed deadline it was time to switch over to PRP testing using PFGW. In a week of PRP testing I've found about six primes, but no twin primes. I estimate that about one in a thousand primes will be part of a twin prime, so finding one in the next nine days requires incredible luck or incredible computing power.

These numbers are over 19,000 digits (over 63,000 bits), so if you happen to find an oreo it will also be the eleventh largest known twin prime, and will be listable on Chris Caldwell's [URL=http://primes.utm.edu/top20/page.php?id=1]Top Twenty Twins Page[/URL]. Let me know if you want to put some computers to work. After June 10th I may return to sieving in an effort to find a listable twin.

William

Agrajag 2004-06-02 03:57

if you send me some pfgw inputs i'd be more than happy to test them for a while - i have a couple of machines here that i can run it on - if you could email [email]phatfil@optusnet.com.au[/email] that'd be great

thanks a lot! :smile:

wblipp 2004-06-02 05:19

[QUOTE=Agrajag]if you could email that'd be great[/QUOTE]

I sent a big chunk, then realized it was large enough that many mailboxes will refuse the attachment. So I zipped it and sent it again. Let me know if you don't get it.

William

Agrajag 2004-06-09 09:34

time's up, guess I wasn't lucky enough :/
thanks a lot anyway!
here's a list of prp's i found in that range (had 4 computers working on different parts of the range):

10000100001154*45007#-1
10000100007604*45007#-1
10000100011400*45007#-1
10000100013880*45007#-1
10000100016626*45007#-1
10000100027119*45007#-1
10000100029300*45007#-1
10000100030374*45007#-1
10000100034759*45007#-1
10000100045165*45007#-1
10000100050352*45007#-1
10000100067637*45007#-1
10000100068769*45007#-1
10000100069793*45007#-1
10000100071160*45007#-1
10000100074401*45007#-1

10000100309043*45007#-1
10000100309745*45007#-1
10000100310663*45007#-1
10000100316772*45007#-1
10000100318505*45007#-1
10000100331208*45007#-1

10000100621073*45007#-1
10000100632859*45007#-1
10000100636178*45007#-1
10000100638029*45007#-1
10000100647055*45007#-1
10000100647299*45007#-1

10000100800753*45007#-1
10000100806036*45007#-1
10000100813427*45007#-1
10000100822318*45007#-1
10000100822638*45007#-1
10000100830454*45007#-1
10000100835194*45007#-1
10000100841890*45007#-1
10000100847089*45007#-1
10000100854782*45007#-1
10000100858481*45007#-1
10000100858863*45007#-1
10000100868965*45007#-1
10000100873980*45007#-1
10000100875969*45007#-1
10000100879221*45007#-1
10000100879403*45007#-1


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