mersenneforum.org  

Go Back   mersenneforum.org > Factoring Projects > Factoring

Reply
 
Thread Tools
Old 2020-01-05, 08:05   #1
qq1010903229
 
Oct 2019

1 Posts
Default I want to factor the cofactor of M1213(Cunningham 2,1213-) in NFS@Home.

I want to factor the cofactor of M1213(Cunningham 2,1213-) in NFS@Home.
qq1010903229 is offline   Reply With Quote
Old 2020-01-05, 10:43   #2
rudy235
 
rudy235's Avatar
 
Jun 2015
Vallejo, CA/.

16748 Posts
Default

Quote:
Originally Posted by qq1010903229 View Post
I want to factor the cofactor of M1213(Cunningham 2,1213-) in NFS@Home.
That number C297 has been First in the More Wanted list since May 2016, Good luck!
Code:
Twenty-Four More Wanted:

	2,1213-	C297
	2,1019+	C223
	2,1934M	C225
	2,1954M	C246
	2,1982M	C249
	3,619-	C207
	3,619+	C272
	3,631+	C219
	5,431-	C266
	5,424+	C282
	5,431+	C292
	6,391-	C274
	6,389+	C242
	6,391+	C260
	7,356+	C207
	10,323-	C271
	10,302+	C289
	10,304+	C282
	10,311+	C223
	11,292+	C259
	12,271-	C234
	12,277-	C285
	12,271+	C250
	12,274+	C213
rudy235 is offline   Reply With Quote
Old 2020-01-05, 11:02   #3
R.D. Silverman
 
R.D. Silverman's Avatar
 
Nov 2003

164318 Posts
Default

Quote:
Originally Posted by qq1010903229 View Post
I want to factor the cofactor of M1213(Cunningham 2,1213-) in NFS@Home.
WHY?

There are Cunningham numbers that have been waiting ~60 years to be factored.
What is special about this one? It is not even the first hole in its table.

And, if you have been paying attention, you would notice that it is ~128 bits larger
than the largest number sieved so far by NFS@Home. That number took 6 weeks
to sieve. I suggest that you estimate how long M1213 would take. Estimate
the required memory for the LA while you are at it.

There are a lot of numbers that I would like to factor. It doesn't mean that it is
possible to do so.
R.D. Silverman is offline   Reply With Quote
Old 2020-01-05, 17:24   #4
VBCurtis
 
VBCurtis's Avatar
 
"Curtis"
Feb 2005
Riverside, CA

101658 Posts
Default

Quote:
Originally Posted by qq1010903229 View Post
I want to factor the cofactor of M1213(Cunningham 2,1213-) in NFS@Home.
If you mean that you're voting for NFS@home to do this number soon, Mr Silverman explained why that isn't in the plan.

If you mean that you want to factor it yourself, Amazon has the hardware you need, right at your fingertips. 33-bit large primes are not optimal, one reason this number is better done outside NFS@home. Good luck!
VBCurtis is offline   Reply With Quote
Old 2020-01-05, 18:41   #5
R.D. Silverman
 
R.D. Silverman's Avatar
 
Nov 2003

3×13×191 Posts
Default

Quote:
Originally Posted by VBCurtis View Post
If you mean that you're voting for NFS@home to do this number soon, Mr Silverman explained why that isn't in the plan.

If you mean that you want to factor it yourself, Amazon has the hardware you need, right at your fingertips. 33-bit large primes are not optimal, one reason this number is better done outside NFS@home. Good luck!
You will also need a significantly larger sieving area for each special-q, as well as larger
factor bases. It will probably need 35 or 36 bit large primes with three on each side.

This would necessitate a rebuilding of the NFS@Home client, as well as significantly
more memory per client core. This, in turn, will sharply reduce the number of available
cores because many machines will not have enough memory.

A very rough estimate of the required sieve time gives about 7 to 8 years, assuming no
loss of resources due to memory requirements. [every 6 to 7 digit increase doubles
the run time].

OTOH Amazon will have many more cores to run the client.

I would be quite pleased to see this number factored. Go for it! I suggest running
a t75 ECM effort first. t65 has been run.
R.D. Silverman is offline   Reply With Quote
Old 2020-01-05, 19:08   #6
R.D. Silverman
 
R.D. Silverman's Avatar
 
Nov 2003

3·13·191 Posts
Default

Quote:
Originally Posted by R.D. Silverman View Post
You will also need a significantly larger sieving area for each special-q, as well as larger
factor bases. It will probably need 35 or 36 bit large primes with three on each side.

This would necessitate a rebuilding of the NFS@Home client, as well as significantly
more memory per client core. This, in turn, will sharply reduce the number of available
cores because many machines will not have enough memory.

A very rough estimate of the required sieve time gives about 7 to 8 years, assuming no
loss of resources due to memory requirements. [every 6 to 7 digit increase doubles
the run time].

OTOH Amazon will have many more cores to run the client.

I would be quite pleased to see this number factored. Go for it! I suggest running
a t75 ECM effort first. t65 has been run.
Would anyone care to estimate the probability that the OP will reply? I'd like to know
why he/she thinks this number warrants special attention.
R.D. Silverman is offline   Reply With Quote
Old 2020-01-06, 04:40   #7
Dylan14
 
Dylan14's Avatar
 
"Dylan"
Mar 2017

1E416 Posts
Default

Quote:
Originally Posted by R.D. Silverman View Post
Would anyone care to estimate the probability that the OP will reply? I'd like to know
why he/she thinks this number warrants special attention.
I have a feeling we scared him off, considering how much effort the number requires. The only reasons I could think of that he would come back would be

1. He has the resources to do it, and he's announcing his intentions (but in that case it would probably be better to contact Wagstaff himself), or
2. He's got a "new" way to factor numbers, which would most likely be debunked and he'd be labelled as a crank.
Dylan14 is offline   Reply With Quote
Old 2020-01-06, 05:07   #8
R.D. Silverman
 
R.D. Silverman's Avatar
 
Nov 2003

3·13·191 Posts
Default

Quote:
Originally Posted by Dylan14 View Post
I have a feeling we scared him off, considering how much effort the number requires. The only reasons I could think of that he would come back would be

1. He has the resources to do it, and he's announcing his intentions (but in that case it would probably be better to contact Wagstaff himself), or
2. He's got a "new" way to factor numbers, which would most likely be debunked and he'd be labelled as a crank.
He also might come back because he has some academic integrity and wants
to reply to a legitimate question: What is special about this number? He might
also come back because he genuinely wants to learn the details.
R.D. Silverman is offline   Reply With Quote
Old 2020-01-06, 05:41   #9
pinhodecarlos
 
pinhodecarlos's Avatar
 
"Carlos Pinho"
Oct 2011
Milton Keynes, UK

5×919 Posts
Default

Same post on here: https://escatter11.fullerton.edu/nfs...ead.php?id=763
pinhodecarlos is online now   Reply With Quote
Old 2020-01-09, 00:22   #10
R.D. Silverman
 
R.D. Silverman's Avatar
 
Nov 2003

3×13×191 Posts
Default

Quote:
Originally Posted by pinhodecarlos View Post
I gave some details about why the number is currently out of reach.

The least the OP could do is show a little courtesy by responding to my question
about why the number is important. Or is he just going to post then vanish?
R.D. Silverman is offline   Reply With Quote
Old 2020-01-09, 02:57   #11
axn
 
axn's Avatar
 
Jun 2003

110308 Posts
Default

There is a not-insignificant probability that OP is a spammer who chose a semi-plausible first post to get thru moderation. I suggest you all ignore this thread until such time as OP comes back with an appropriate response.
axn is online now   Reply With Quote
Reply

Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
SNFS of C112 cofactor of 608^60+480^76 sean YAFU 22 2017-05-20 17:05
Cofactor Search carpetpool Information & Answers 4 2016-12-12 04:35
122^99+99^122 cofactor, matrix not dense enough, retrying pinhodecarlos NFS@Home 2 2016-10-18 17:43
Formula for cofactor for Fermat numbers. literka Factoring 7 2012-04-05 09:51
Certification of a 10064 bit prp cofactor MatWur-S530113 PrimeNet 9 2010-02-16 12:52

All times are UTC. The time now is 06:13.

Thu Jul 9 06:13:57 UTC 2020 up 106 days, 3:47, 0 users, load averages: 1.80, 1.62, 1.46

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.

This forum has received and complied with 0 (zero) government requests for information.

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation.
A copy of the license is included in the FAQ.