PrimeGrid
Please visit donation page to help the project cover running costs for this month

Toggle Menu

Join PrimeGrid

Returning Participants

Community

Leader Boards

Results

Other

drummers-lowrise

Advanced search

Message boards : Cullen/Woodall prime search : Welcome to the Cullen/Woodall Prime Search

Author Message
ReggieProject donor
Volunteer moderator
Project administrator
Volunteer tester
Project scientist
Send message
Joined: 10 May 14
Posts: 241
ID: 311759
Credit: 270,388,457
RAC: 180,168
Discovered 1 mega primeFound 1 prime in the 2018 Tour de PrimesFound 1 mega prime in the 2018 Tour de Primes321 LLR Turquoise: Earned 5,000,000 credits (5,037,769)Cullen LLR Ruby: Earned 2,000,000 credits (3,541,849)ESP LLR Ruby: Earned 2,000,000 credits (2,053,710)Generalized Cullen/Woodall LLR Turquoise: Earned 5,000,000 credits (5,046,240)PPS LLR Jade: Earned 10,000,000 credits (13,191,766)PSP LLR Turquoise: Earned 5,000,000 credits (5,022,331)SoB LLR Turquoise: Earned 5,000,000 credits (5,125,022)SR5 LLR Turquoise: Earned 5,000,000 credits (5,046,188)SGS LLR Ruby: Earned 2,000,000 credits (2,682,790)TRP LLR Ruby: Earned 2,000,000 credits (2,016,337)Woodall LLR Ruby: Earned 2,000,000 credits (2,012,569)321 Sieve (suspended) Amethyst: Earned 1,000,000 credits (1,000,211)Cullen/Woodall Sieve Sapphire: Earned 20,000,000 credits (20,006,134)Generalized Cullen/Woodall Sieve (suspended) Ruby: Earned 2,000,000 credits (2,000,420)PPS Sieve Sapphire: Earned 20,000,000 credits (22,440,747)AP 26/27 Sapphire: Earned 20,000,000 credits (20,526,311)GFN Emerald: Earned 50,000,000 credits (83,392,894)WW (retired) Emerald: Earned 50,000,000 credits (50,172,000)PSA Sapphire: Earned 20,000,000 credits (20,070,245)
Message 116530 - Posted: 28 Mar 2018 | 15:59:24 UTC
Last modified: 23 Sep 2020 | 0:40:17 UTC

Welcome to the Cullen/Woodall Prime Search

A Cullen number is in the form of n*2^n+1. Fr. James Cullen first studied these numbers in 1905 because they have interesting divisibility properties. It is conjectured that there are infinitely many n values that will yield Cullen primes, though it has been shown that almost all are composite.

Further reading:
Cullen Number on Wikipedia
Top Twenty Cullen Primes in Chris Caldwell's Database

The following n values yield prime Cullen numbers (OEIS A005849) (ones found at PrimeGrid highlighted):

1, 141, 4713, 5795, 6611, 18496, 32292, 32469, 59656, 90825, 262419, 361275, 481899, 1354828, 6328548, and 6679881.

A Woodall number is in the form n*2^n-1. They are named after Herbert J. Woodall in 1917, when he studied them and their divisibility properties after being inspired by Fr. James Cullen. They are also called Cullen numbers of the second kind. Similarly to Cullen numbers, it is conjectured that there are infinitely many n values that will yield Woodall primes, though it has been shown that almost all are composite.

Further reading:
Woodall Number on Wikipedia
Top Twenty Woodall Primes in Chris Caldwell's Database

The following n values yield prime Woodall numbers (OEIS A002234) (ones found at PrimeGrid highlighted):

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 17016602.

Message boards : Cullen/Woodall prime search : Welcome to the Cullen/Woodall Prime Search

[Return to PrimeGrid main page]
DNS Powered by DNSEXIT.COM
Copyright © 2005 - 2023 Rytis Slatkevičius (contact) and PrimeGrid community. Server load 2.00, 2.38, 2.13
Generated 25 Sep 2023 | 12:07:28 UTC