20160219, 05:17  #1 
Bemusing Prompter
"Danny"
Dec 2002
California
2^{3}×311 Posts 
What's the deal with M4,096?
There are a few computers that keep submitting the factors for M4,096. The funny thing is that the exponent isn't even prime. Anyone know what's going on?

20160219, 06:19  #2  
Romulan Interpreter
"name field"
Jun 2011
Thailand
3·5·683 Posts 
Quote:
Those are all different products (i.e. composite) of known F12 small prime factors. People still do lots of ECM trying to get Mr. Guy's money (edit: or just to make him a present for the 100th bday celebration in September, which would be very nice!) Last fiddled with by LaurV on 20160219 at 06:28 

20160219, 06:32  #3 
Undefined
"The unspeakable one"
Jun 2006
My evil lair
1100111110001_{2} Posts 

20160219, 06:54  #4 
(loop (#_fork))
Feb 2006
Cambridge, England
6454_{10} Posts 
M4096 = F11 x F10 x F9 ... So work on M4096 is effectively on F11 (since the others are fully factored)

20160219, 07:17  #5  
Romulan Interpreter
"name field"
Jun 2011
Thailand
2805_{16} Posts 
Quote:
Joking apart (I know that was a typo/brainfart on your side), you are both wrong, reality is that PrimeNet does not keep the "M" or "F" but only the exponent, which is either a power of 2, or a prime. He distinguish which, by that. (for example, see here) In the "recent work" list, on the exponent column (which is labeled Mn, inadvertently): "4096" means F12 "1061" means M1061 You can report factors for either of them. Like for "1048576" if you like, and PrimeNet knows is a factor of F20, if you have one... The OP saw the exponent in the list of reported factors (someone indeed reported a lot of composite factors of F12 in the last days) and he assumed it is "M". It is not. Therefore my reply. Last fiddled with by LaurV on 20160219 at 07:28 Reason: clarification 

20160219, 07:33  #6 
Bemusing Prompter
"Danny"
Dec 2002
California
2^{3}×311 Posts 
I figured it was F12, but it's weird that the same computers keep sending in the same factors.

20160406, 16:28  #7 
Jan 2005
3E_{16} Posts 
Wouldn't this occur if they set up their worktodo file to do ECM on F12 but didn't include the list (or product) of known factors? (Reminds me of the old engineers joke: as a last resort, read the manual.)

20160406, 17:57  #8 
1976 Toyota Corona years forever!
"Wayne"
Nov 2006
Saskatchewan, Canada
3×5×349 Posts 

20160406, 19:10  #9  
Aug 2002
3·5·569 Posts 
Quote:
http://www.mersenneforum.org/showthread.php?t=106 It starts at post #10 and is very embarrassing since the "factor" ends in a "5". So, when we actually found a factor once, we spent several hours making sure it was a real factor before posting because we didn't want to look stupid again. 

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