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Old 2006-06-21, 23:13   #1
jasong
 
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"Jason Goatcher"
Mar 2005

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Default Don't know how to work on Cunningham numbers.

I compiled ecm a couple weeks ago, so I know it's recent. Basically, I'd like to spend some time on one of my dual-core processor cores doing Cunningham numbers, but I have some questions:

How does the listing format work? If I remember correctly, there are 3 numbers with commas between them. How do I "translate" this into the formula?

Also, and I'm sorry if actually doing the work answers the questions, but I've only done ECMNet and don't know how to do manual work. I looked through the thread titles and nothing jumped out at me as possibly being helpful. If someone wants to assign me 1-2 weeks of "their" work to work on my computer, I'd be glad to help.

Because of some other DC work I'm doing, I'm not actually going to work on this part until Friday or Saturday, but I'm willing to experiment until then to make sure I understand how things work.

Thanks for any help. :)
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Old 2006-06-22, 01:09   #2
fetofs
 
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Cunningham numbers are just 2 with a comma between them. The minus sign is normally put in.
a, b- = a^b - 1

Sometimes you'll find a plus sign, like so:
a, b+ = a^b + 1

If you're talking about homogeneous cunninghams, the formula is:
a, b, n = a^n - b^n

Last fiddled with by fetofs on 2006-06-22 at 01:10
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Old 2006-06-22, 10:06   #3
jasong
 
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Quote:
Originally Posted by fetofs
Cunningham numbers are just 2 with a comma between them. The minus sign is normally put in.
a, b- = a^b - 1

Sometimes you'll find a plus sign, like so:
a, b+ = a^b + 1

If you're talking about homogeneous cunninghams, the formula is:
a, b, n = a^n - b^n
Okay, in that case I have two questions(maybe more later):

(1) What's the best way to reserve?(Should I go to another site to reserve?)

(2) Unfortunately, my room's been rearranged since I did this last, so I need instructions on making the ecm parameters.

Edit: Perhaps instead I should be looking at ecm servers.(I just rediscovered the Cunningham server. Sorry for bugging you guys. :( )

Last fiddled with by jasong on 2006-06-22 at 10:29
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Old 2006-06-22, 14:39   #4
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Are you aware of the Cunningham tables here on MersenneForum at

http://www.mersenneforum.org/forumdisplay.php?f=51

From here you can see that 3523-1 has a 233 digit composite that has had some work done at B1=110M. You can copy the decimal digits to a file and the start ecm from a command prompt as

ecm 110000000 < file.txt >> results.txt
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Old 2006-06-23, 01:08   #5
jasong
 
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Quote:
Originally Posted by wblipp
Are you aware of the Cunningham tables here on MersenneForum at

http://www.mersenneforum.org/forumdisplay.php?f=51
Actually, my original intention was to attempt those forum numbers. But since I seem to be accomplishing something very similar, and far easier, by connecting to the Cunningham server, instead of doing it manually, I've decided to go that route.

Thanks for pointing out the forum to me, though :)
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Old 2006-06-27, 13:50   #6
R.D. Silverman
 
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Quote:
Originally Posted by wblipp
Are you aware of the Cunningham tables here on MersenneForum at

http://www.mersenneforum.org/forumdisplay.php?f=51

From here you can see that 3523-1 has a 233 digit composite that has had some work done at B1=110M. You can copy the decimal digits to a file and the start ecm from a command prompt as

ecm 110000000 < file.txt >> results.txt

Note:

Some of those tables are quite a bit out of date. A lot of numbers
have been finished since the tables were last modified.

Sam Wagstaff's web site contains more recent info.
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Old 2006-06-30, 08:51   #7
akruppa
 
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"Nancy"
Aug 2002
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I've removed those numbers from our tables that are not in Sam's composites list (as of June 2006) anymore. Some remaining composites may have gotten smaller, though.

Alex
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