mersenneforum.org I want to factor the cofactor of M1213(Cunningham 2,1213-) in NFS@Home.
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 2020-01-05, 08:05 #1 qq1010903229   Oct 2019 1 Posts 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.
2020-01-05, 10:43   #2
rudy235

Jun 2015
Vallejo, CA/.

16748 Posts

Quote:
 Originally Posted by qq1010903229 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

2020-01-05, 11:02   #3
R.D. Silverman

Nov 2003

164318 Posts

Quote:
 Originally Posted by qq1010903229 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.

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.

2020-01-05, 17:24   #4
VBCurtis

"Curtis"
Feb 2005
Riverside, CA

101658 Posts

Quote:
 Originally Posted by qq1010903229 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!

2020-01-05, 18:41   #5
R.D. Silverman

Nov 2003

3×13×191 Posts

Quote:
 Originally Posted by VBCurtis 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.

2020-01-05, 19:08   #6
R.D. Silverman

Nov 2003

3·13·191 Posts

Quote:
 Originally Posted by R.D. Silverman 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.

2020-01-06, 04:40   #7
Dylan14

"Dylan"
Mar 2017

1E416 Posts

Quote:
 Originally Posted by R.D. Silverman 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.

2020-01-06, 05:07   #8
R.D. Silverman

Nov 2003

3·13·191 Posts

Quote:
 Originally Posted by Dylan14 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
also come back because he genuinely wants to learn the details.

 2020-01-06, 05:41 #9 pinhodecarlos     "Carlos Pinho" Oct 2011 Milton Keynes, UK 5×919 Posts Same post on here: https://escatter11.fullerton.edu/nfs...ead.php?id=763
2020-01-09, 00:22   #10
R.D. Silverman

Nov 2003

3×13×191 Posts

Quote:
 Originally Posted by pinhodecarlos Same post on here: https://escatter11.fullerton.edu/nfs...ead.php?id=763
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?

 2020-01-09, 02:57 #11 axn     Jun 2003 110308 Posts 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.

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