Woodall Primes: Definition and Status

News Flash!

On December 21, 2007, Matthew Thompson, participating in the PrimeGrid project, found the largest known Woodall prime, the first mega-digit Woodall, 3752948*2^3752948-1

News Flash!

On August 13, 2007, Stephen Kohlman, participating in the PrimeGrid project, found the largest known Woodall prime, 2367906*2^2367906-1

News Flash!

On August 4, 2007, Lasse Mejling Andersen, participating in the PrimeGrid project, found the largest known Woodall prime, 2013992*2^2013992-1

News Flash!

On June 5, 2007, Willem Siemelink found the largest known Woodall prime, 1467763*2^1467763-1

News Flash!

On January 25, 2007, Willem Siemelink found the Woodall prime, 1268979*2^1268979-1

Woodall Primes are Woodall numbers that are prime and of the form Wn = n*2n-1.

Wn is prime for n = 2, 3, 6, 30, 75, 81, 115, 123, 249, 362, 384, 462, 512, 751, 822, 5312, 7755, 9531, 12379, 15822, 18885, 22971, 23005, 98726, 143018, 151023, 667071, 1195203, 1268979, 1467763, 2013992, 2367906, 3752948 and for no other n < 4,750,000. Chris Caldwell maintains the top 20 Woodall Page.

A table of ranges of exponents that have already been tested or are reserved/available for current testing for Woodall primes is available.

A list of contributors to the Woodall project is here.

To search for Woodall primes, the recommended software is

To participate in a distributed search for Woodall primes, go here

To reserve a free range of n for one of the numbers above, check the most recent reserved values of n also and then click on the link on that page to reserve your range.

To search for Woodall Primes of other bases, check out Steven Harvey's Generalized Woodall Search

Cullen numbers (Cn = n*2n+1) are related to Woodall numbers. Check here for the Cullen prime search.


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If you have any questions about the Woodall Search, you can e-mail Mark Rodenkirch or Ray Ballinger

URL: http://www.prothsearch.net/woodall.html
Last Modified: September 8, 2008