On 23 Mar 2008, 7:57:28 UTC, PrimeGrid, in collaboration
with 321 Search, found another Mega Prime.
The discovery was made by Dylan Bennett of Canada using an
Intel C2D @ 1.66 GHz with 2 GB RAM running Linux. This
computer took almost 15 hours and 30 minutes to complete
the primality test.
The prime was verified on 2 Apr 2008, 5:13:16 UTC, by Dave
Pickles of Canada using an AMD Athlon XP 2500+ with 512 MB
RAM running Windows 2000. This computer took 18 hours 42
minutes to complete the primality test.
This is PrimeGrid's second mega prime and 321 Search's
first. It is their 11th prime overall and the second
largest found mega-digit prime using LLR. Since the search
began, just over 74108 tests have been completed by 4331
users using 7454 computers.
Using a single PC would have taken years to find this
prime. So this timely discovery would not have been
possible without the thousands of volunteers who
contributed their spare CPU cycles. A special thanks to
everyone who contributed their advice and/or computing
power to the search - especially Paul Underwood and the
PrimeGrid's Woodall Prime Search will continue to search
for even larger Woodall Primes. To join the search please
visit PrimeGrid: www.primegrid.com
Rytis Slatkevicius, the developer of PerlBOINC - a
Perl-language-based port of the BOINC platform, created
PrimeGrid as a test project for PerlBOINC. PrimeGrid's
first sub-project was in cryptography as it participated in
the RSA Factoring Challenge. While it no longer
participates in the challenge, PrimeGrid continues to
expand its functionality. Currently the project is running
the following sub-projects:
More projects are available in PrimeGrid's Project
Staging Area. Here, you can get a "sneak" preview as
projects are prepared for entry into full BOINC production.
Other individual projects may also be avialable in this
area for you to test.
- Twin Prime Search: searching for gigantic twin primes
of the form k*2^n + 1 and k*2^n - 1.
- Cullen-Woodall Search: searching for mega primes of
forms n*2^n + 1 and n*2^n - 1.
- 3*2^n-1 Search: searching for mega primes of the form
3*2^n - 1.
- Prime Sierpinski Project: helping Prime Sierpinski
Project solve the Prime Sierpinski Problem.
For more information, please visit PrimeGrid: www.primegrid.com
About 321 Search
321 Search began in February 2003 from a post by Paul
Underwood seeking help from interested parties in a prime
search attempt of the form 3*2^n-1. The initial goal was to
build upon the completed work at Proth Search and extend
the list of known primes to an exponent of 1 million.
Interests gathered quickly and by the time they reached n=1
million, they had already pre-sieved further.
At that time, using George Woltman's libraries which
implemented the newly discovered method of IBDWT
(irrational base discrete weighted transform)
multiplication of Colin Percival, Jean Penne's LLR
(Lucas-Lehmer-Riesel) computer program gave them a rate
boost of 400%. This together with computer hardware
advances allowed them to reach tests at 1 million digits or
exponent of about 3.3 million within a few years, with
stated aim of eventually finding a mega-prime.
A note from Paul Underwood
For more information, please visit 321 Search:
In the early days, 321 Search relied on word of mouth at
Yahoo groups to recruit people, but soon were kindly
invited by Mike Vang a.k.a. "Xyzzy" to have their own sub
forum at www.mersenneforum.org.
There we congregated to discuss the search and to develop a
few administration scripts for such things as participant
point statistics and reservations. All this was manually
maintained until we joined forces with PrimeGrid who had a
proper server using BOINC (Berkeley Open Infrastructure for
I see the future of the search for "321 primes" dependent
on PrimeGrid, because the administration is relatively
minimal and the double checking done by them highly limits
computation errors, which increase with ever larger tests;
plus it is easy for a contributor to link to and use the
server. The original band of 321 Search will remain in
existence for the foreseeable future too.
I cannot thank enough all of the people who have helped --
with discussion, administration and computer resources.
BOINC (Berkeley Open Infrastructure for Network Computing)
is a software platform for distributed computing using
volunteered computer resources. It allows users to
participate in multiple distributed computing projects
through a single program. Currently BOINC is being
developed by a team based at the University of California,
Berkeley led by David Anderson.
For more information, please visit BOINC: boinc.berkeley.edu