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Message boards : Project Staging Area : 2015 PRPNet December Challenge

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Roger
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Message 90095 - Posted: 30 Nov 2015 | 14:51:14 UTC

121 - Binomial Challenge - 01-11 December

Announced is a challenge at the 121 prime search project from the 1st till 11th of December. I suggest we start at 12:00 UTC and end at 12:00 UTC.

A Binomial number is an integer obtained by evaluating a polynomial containing two terms, also called a binomial. The form of this binomial is x^n +/- y^n. Binomial numbers are a generalization of Cunningham numbers, and the Cunningham numbers are Binomial numbers where y = 1. Other subsets of the Binomial numbers are the Mersenne numbers and the Repunits.

December 4th is the 884th anniversary of the passing of Omar Khayyám, a Persian mathematician, astronomer, philosopher, and poet, who is widely considered to be one of the most influential scientists of the middle ages. He wrote numerous treatises on mechanics, geography, mineralogy and astronomy. Khayyám was famous during his times as a mathematician. He wrote the influential Treatise on Demonstration of Problems of Algebra (1070), which laid down the principles of algebra, part of the body of Mathematics that was eventually transmitted to Europe. In particular, he derived general methods for solving cubic equations and even some higher orders. In the Treatise, he wrote on the triangular array of binomial coefficients known as Pascal's triangle.

More about the 27121 prime search can be found here. News and infos about the PRPNet client can be found here.

To take part, you have to activate the following lines in prpclient.ini:

server=121:100:1:prpnet.primegrid.com:12001

Stats will be available at the well known place here.

All previous PRPNet challenge stats can be found here.

Good luck!
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JeppeSN

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Message 90103 - Posted: 30 Nov 2015 | 18:38:20 UTC - in response to Message 90095.

But was this challenge not supposed to combine the 27 project (port 12006) with the 121 project (port 12001)? /JeppeSN

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Message 90104 - Posted: 30 Nov 2015 | 19:57:22 UTC - in response to Message 90103.

But was this challenge not supposed to combine the 27 project (port 12006) with the 121 project (port 12001)? /JeppeSN

in earlier plans there was a combined, in latest plans a 121-only
i prepared the stats for 121-only
as of now, there is no time to change the stats to a combined challenge; sorry for this.

EDIT: and the short time between last and upcoming challenge was a internal challenge between my real life and my hobby, too ;-)
____________
my current lucky number: 3749*2^1555697+1
PSA-PRPNet-Stats-URL: http://u-g-f.de/PRPNet/

Roger
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Message 90129 - Posted: 1 Dec 2015 | 11:55:22 UTC

Challenge has started!

For info, there are nine tests on the -1 side that errored out and were never sent out again by the server. That's why the -1 side is completed thru 5,824,723 while the +1 side is completed thru 6,406,328. Those have now been requeued and after they complete the server statistics page should look a lot more normal. BTW I am currently running 3 of those 9.

Omar Khayyám:

Be happy for this moment. This moment is your life.

The thoughtful soul to solitude retires.

Myself when young did eagerly frequent doctor and saint, and heard great argument about it and about: but evermore came out by the same door as in I went.

Roger
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Message 90260 - Posted: 6 Dec 2015 | 22:06:43 UTC

We've reached half way through the challenge. Leading edge now up to 6,485,444 on the plus and 6,485,457 on the minus side.
121 sub-project has now passed the 100,000 WU's completed milestone.
If you haven't noticed there are graphs available on PRPNet stats for Users and Teams for each sub-project. Just choose who you are interested in on the far right drop down lists.
Grebuloner and Aggie_The_Pew currently in the lead.

JeppeSN

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Message 90270 - Posted: 7 Dec 2015 | 13:43:31 UTC

While we wait for the unlikely, here are the currently known exponents in the k=121 series. The plus form:

8; 12; 44; 84; 96; 228; 264; 320; 732; 788; 1,808; 7,928; 12,264; 37,784; 59,196; 91,112; 112,208; 168,716; 251,184; 264,632; 272,052; 513,020; 636,564; 674,360; [searched to over 6,400,000]

The minus form:

1; 3; 21; 27; 37; 43; 91; 117; 141; 163; 373; 421; 1,581; 2,035; 10,701; 18,931; 21,307; 51,195; 64,579; 156,541; 302,097; 334,257; 368,059; 383,061; 410,131; 494,317; 541,621; 990,219; 1,039,965; 1,526,097; 1,589,157; 1,695,499; 1,954,243; 2,033,941, 4,553,899; [searched to over 6,400,000]

The beginning of these sequences can be found with GP/PARI with code like:

for(n=0,10^5,ispseudoprime(121<<n+1)&&print1(n,", ")) for(n=0,10^5,ispseudoprime(121<<n-1)&&print1(n,", "))

The end of the sequences can be found by a proper search at the Prime Pages. The sequences are in OEIS as A032410 and A050586.

These have been posted in these forums before, see e.g. this July 2014 post by user John.

What I wonder is if the gap from 674,360 to over 6,400,000 is actually real. It seems strange, except if there is some reason we have not thought of. Or maybe we have deliberately skipped a range?

/JeppeSN

JimB
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Message 90275 - Posted: 7 Dec 2015 | 14:39:01 UTC - in response to Message 90270.

We haven't skipped any range that I know of. Right before the beginning of the challenge there were eight candidates from two years ago that hadn't been properly tested. I forced them to be retested (none prime). Every candidate I looked at did actually have a residue but of course they're not doublechecked. Residues from the k=27 and k=121 ports get placed into our BOINC imported residues table and they'll be doublechecked on BOINC some day.

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Message 90336 - Posted: 11 Dec 2015 | 14:52:49 UTC

Challenge is over, the year 2015 soon too!
Congratulation to Grebuloner and Aggie_The_Pew
Final ranks are as follows

top users 1 Grebuloner 862 32,661,134 2 TheDawgz 802 30,652,140 3 Lumiukko 487 18,536,289 4 Paperboy 394 14,971,014 5 Williamd007 280 10,639,809 top teams 1 Aggie_The_Pew 1,606 61,129,666 2 The_Knights_Who_Say_Ni! 1,202 45,574,851 3 PrimeSearchTeam 619 23,556,071 4 L'Alliance_Francophone 223 8,458,297 5 Sicituradastra. 133 5,085,101

Thank you for your support and patience.
I hope you enjoyed the challenge series and you will be back next year!
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