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 2008-06-10, 22:53 #1 Flatlander I quite division it     "Chris" Feb 2005 England 31·67 Posts Reportable Twin Found Hi I have found a top 10 twin, what do I type in the prime submission box? Chris
 2008-06-10, 23:01 #2 Mini-Geek Account Deleted     "Tim Sorbera" Aug 2006 San Antonio, TX USA 2·3·23·31 Posts Judging by the twins already there, I'd guess: Code: k*2^n-1 Twin (p) k*2^n+1 Twin (p+2) Congrats, hope that works.
 2008-06-10, 23:12 #3 Flatlander I quite division it     "Chris" Feb 2005 England 40358 Posts That worked, thank you. 108615*2^110342+-1 is twin prime! Comes in at 7th place
 2008-09-12, 11:46 #4 Flatlander I quite division it     "Chris" Feb 2005 England 31×67 Posts Update Since finding this twin, I have spent most of my CPU time searchng for a record twin < n=333,333. So far I've found lots of Riesels, but no twin. I'd would be nice to hold the record even if it's only for a short while.
 2009-12-15, 16:36 #5 Flatlander I quite division it     "Chris" Feb 2005 England 31×67 Posts Just for fun ... Now that finding the world's biggest twin is (realistically) out of my reach, I decided to set myself a different challenge. Thus: 23321624*3^53005+-1 is twin. Buzz Aldrin was described by David Letterman as 'The first man named Buzz to walk on the moon.' Well, this is the world's biggest twin not of the form k*2^n+-1. Found with NewPGen and the go-faster WinPFGW. (A new proof-code, so there might be a delay before it makes the list.)
2010-11-12, 15:01   #6
Puzzle-Peter

Jun 2009

23·3·29 Posts

Quote:
 Originally Posted by Flatlander Now that finding the world's biggest twin is (realistically) out of my reach, I decided to set myself a different challenge. Thus: 23321624*3^53005+-1 is twin. Buzz Aldrin was described by David Letterman as 'The first man named Buzz to walk on the moon.' Well, this is the world's biggest twin not of the form k*2^n+-1.
Funny idea! I decided to give it a try and after quite a number of CPU cycles I came up with

22835841624*7^54321+-1 is twin

Last fiddled with by Puzzle-Peter on 2010-11-12 at 15:01

2010-11-12, 15:23   #7
rajula

"Tapio Rajala"
Feb 2010
Finland

4738 Posts

Quote:
 Originally Posted by Puzzle-Peter 22835841624*7^54321+-1 is twin
Congratulations!
That's a nice twin. It also looks nice on its place as 7th largest twin (among all those dull power-two twins)!

2010-11-12, 17:56   #8
Flatlander
I quite division it

"Chris"
Feb 2005
England

31·67 Posts

Quote:
 Originally Posted by Puzzle-Peter Funny idea! I decided to give it a try and after quite a number of CPU cycles I came up with 22835841624*7^54321+-1 is twin
Wow! That's much bigger. How long did it take?

2010-11-12, 19:27   #9
Puzzle-Peter

Jun 2009

12708 Posts

Quote:
 Originally Posted by Flatlander Wow! That's much bigger. How long did it take?
It took about 1.7M tests, each one about 80-140 seconds, depending on the machine. Plus a week of sieving on one quad.

I guess I was lucky. I had a minus prime each 1900 tests. So I expected 1900*1900~3.5M tests, but needed only half of that.

Last fiddled with by Puzzle-Peter on 2010-11-12 at 19:28

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