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GIMPS newsletter #18, 25 September, 2001

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The Mersenne Newsletter, issue #18 September 25, 2001


1. Welcome
2. Faster version 21 now available
3. New versions for other processors
4. Handy utility for NT/2000/XP users found
5. Progress since last newsletter
6. Nayan Hajratwala claims $50,000 EFF award

1. Welcome

It has been nearly 2 years since the last newsletter. Welcome to
all the new GIMPS members that have joined since that time.

2. Faster version 21 now available

Version 21 is now available and it is up to 25% faster for Athlon,
Pentium III, and Celeron 2 processors. Version 21 also contains SSE2
code for the Pentium 4 - a whopping 3 times faster than version 20!

You can get the new version at
You'll find a complete list of version 21's new features at

To upgrade, stop and exit the current version. Optionally
make a backup of the directory. Install the new version on top of the
old version. Start the new version of the program.

You can upgrade immediately without waiting for any work to complete.

A warning to overclockers: This new version runs faster, putting a little
more stress on your machine. You should run the torture test before
resuming tests with the new version.

3. New versions for other processors

Over the last two years Ernst Mayer and Guillermo Ballester Valor
have improved their Mersenne prime testers for UNIX and Macintosh machines.
See and if interested.

4. Handy utility for NT/2000/XP users found

I've found a nifty utility that lets prime95 run as a service under
Windows NT/2000/XP. This is much better than the ntprime program I wrote
because you will now have access to user interface. To try it out follow
the instructions for firedaemon at

5. Progress since last newsletter

While GIMPS has been rather unlucky in not finding a new Mersenne prime
the last two years, we have made a great deal of progress. The following
milestones have taken place for exponents below 20,400,000:

* All exponents below M(6972593) tested at least once.
* Double-checking proved M(2976221) and M(3021377) are the
36th and 37th Mersenne primes.
* Over 44,000 exponents eliminated by factoring.
* Over 70,000 double-checks completed.
* Over 100,000 exponents tested for the first time!

For those testing 10,000,000 digit numbers, 159 primality tests have been
completed. While winning the $100,000 EFF award for finding a 10,000,000
digit prime looked unlikely two years ago, today's fastest P4 CPU can complete
the test in under a month and a half. Now, if we only had access to 100,000
of these machines...

You can watch the hourly progress of the search on the server's
status page at and
weekly status at

6. Nayan Hajratwala claims $50,000 EFF award

Congratulations go to Nayan who On April 6th last year, claimed
the EFF award for discovering the first known 1,000,000 digit prime!
See the Electronic Frontier Foundation's web site at for more details.

To see the GIMPS prize rules for distributing the $100,000 EFF award
for discovery of a 10,000,000 digit prime, visit


GIMPS is powered and sponsored by Entropia, Inc. Entropia's distributed
computing software powers high-performance PC computing grids for
Fortune 500 business enterprises and Internet research projects,


My thanks go to all GIMPS participants for contributing their spare CPU
cycles. During the last 5 years, we've accomplished more Mersenne prime
research than I ever could have imagined! Keep up the good work.
Hopefully, we'll find the 39th known Mersenne prime soon!!


George Woltman


Scott Kurowski, founder, Entropia Inc.