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GIMPS newsletter #4, 11 June, 1996

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The Mersenne Newsletter, issue #4 June 11, 1996


Since the last newsletter 60 days ago, we've added 50 new members to
our ranks. This brings to more than 140 people and an estimated 170+
computers involved in the search. Welcome to all the new searchers!


Also over the past 60 days, we've proven a whopping 3,743 Mersenne
numbers composite! This leaves us with only 21,865 untested Mersenne
numbers with exponents below 1,300,000. If you use a 90 MHz Pentium
as a standard, these numbers can be tested in just over 103 CPU years.

For those that would like a breakdown, here are the number of exponents
that need testing in each 100,000 range:

300000-400000 49
400000-500000 357
500000-600000 2084
600000-700000 2625
700000-800000 3030
800000-900000 2891
900000-1000000 2760
1000000-1100000 3040
1100000-1200000 2819
1200000-1300000 2210

We're making such good progress that I opened up the exponents from
1,300,000 to 2,630,000 for testing! This should keep us busy well
into the next century.

Furthermore, 486 users have double-checked most of the Mersenne
exponents below 140,000.


Many thanks to Luther Welsh for organizing the Mersenne mailing list.
There have been several interesting discussions on various topics
related to the mathematics of Mersenne numbers as well as the
computer algorithms that deal with them. If interested, check it
out at

Program News

On May 22, a new version of the program was placed on the web.
The most important new features of this version are a 10% speed
increase in running Lucas-Lehmer tests and more error checking
to insure accurate results! You can download the program from
I recommend everyone upgrade to this version at their earliest convenience.

On June 11, a minor update was made to the Windows 95 version. This
version allows you to run the program for a specified amount of time.
It also lets you pick a different priority to run the program.

As always, comments and suggestions for future enhancements are welcome.

Happy hunting,
George Woltman