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
entire 321 Search
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 Network Computing.)
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
I cannot thank enough all of the people who have helped
-- with discussion, administration and computer
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