20080113, 22:08  #1 
"Jason Goatcher"
Mar 2005
5·701 Posts 
Cullen and Woodall altering on Prime Pages
Okay, I understand that if a k in k*2^n+/1 is even than k can be halved and n increased by one. But since Cullen and Woodall numbers are based on the idea that k and n are the same number, doesn't Prime Pages policy defeat the purpose of the people doing the search in the first place?

20080115, 21:50  #2  
"Brian"
Jul 2007
The Netherlands
7×467 Posts 
Quote:
What is this Prime Pages policy? Brian. 

20080116, 10:30  #3  
"Jason Goatcher"
Mar 2005
5·701 Posts 
Quote:
With Prime Pages, they've noted that if k is even, then k*2^n+1=(k/2)*2^(n+1)+1. This is normally a fabulous simplification. The problem is the whole point of the Cullen and Woodall projects is that k and n are the same number, when you do the math trick, it's just a regular equation. If there's something quirky about an equation, and simplifying takes away the obviousness of the quirkiness, than you've defeated the whole point of finding it in the first place. Last fiddled with by jasong on 20080116 at 10:31 

20080116, 10:54  #4 
"Brian"
Jul 2007
The Netherlands
7×467 Posts 
But isn't the point of the exercise to factorise the Cullen and Woodall numbers and to find the very rare primes, not to discover the alternative representations of the numbers?
Edit: Ah, are you wondering why Prime Pages doesn't list the numbers with the k equal to the n? I think because it lists other numbers of the form k*2^n +/ 1 which are not Cullen/Woodall as well, and the policy is to "simplify" all such numbers so that n is as large as possible. This makes it indeed less simplelooking in the case of the special Cullen/Woodall, but by standardising in that way they make it less likely that someone will make a mistake by analysing a number which has in fact already been tested but written in a different form. Last fiddled with by BrianE on 20080116 at 11:04 Reason: Suddenly guessed what you are getting at. 
20080117, 06:02  #5 
Jun 2003
2^{3}·607 Posts 
To be fair, Prime Pages' prime (pardon the pun) purpose is to act as a repository of top primes. It is always a good idea to "normalize" the expression of a prime to a standard form so that you don't end up with multiple representations of the same prime.
The secondary purpose of classifying the primes is achieved thru the archival tags. IMO, these policies are entirely appropriate for a catalog such as this. I can see why seeing the original "nonnormalized" representation might be useful, but I just don't think it is prime page's responsibility. 
20080118, 01:23  #6  
"Jason Goatcher"
Mar 2005
5·701 Posts 
Quote:
Jasong knows he has too much free time, but isn't sure how to rectify the situation. 

20080118, 08:16  #7  
Bamboozled!
"πΊππ·π·π"
May 2003
Down not across
3×3,529 Posts 
Quote:
Quote:
Paul Last fiddled with by xilman on 20080118 at 08:16 Reason: Why not? 

20080124, 00:11  #8  
"Jason Goatcher"
Mar 2005
110110110001_{2} Posts 
Quote:
One of my goals, in terms of reorganizing my life, is to learn some programming skills. I haven't even gotten a third of the way through the book because, as I said, it's dry as hell, so all I've really done for the moment is made a list of things I want to purchase and start asking around for old PDAs I could use once I have a system set up to monitor goals. 

20080124, 14:01  #9  
"Mike"
Aug 2002
79×101 Posts 
Quote:
Simplify. 

20080125, 01:51  #10 
"Jason Goatcher"
Mar 2005
5·701 Posts 

Thread Tools  
Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Generalized Cullen and Woodall Searches  rogue  And now for something completely different  40  20201208 13:21 
Generalized Cullen and Woodall numbers  em99010pepe  Factoring  9  20190326 08:35 
Super Cullen & Woodall primes  Citrix  And now for something completely different  1  20171026 09:12 
Generalized Cullen/Woodall Sieving Software  rogue  And now for something completely different  13  20141229 19:11 
Can we add Cullen and Woodall p1ing here?  jasong  Marin's Mersennearies  1  20071118 23:17 