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Old 2008-11-25, 12:10   #56
xilman
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Quote:
Originally Posted by Batalov View Post
(32Β·10^145+13)/9 = 355..557 = 37 Β· 3197004779 . C135
So, while cracking this C135...
Code:
> echo 300581646694173102754989957730357512537506582488896855340284419687744533384371572427030444849066320698471799488342573090961576245101059 | ~/bin/ecm -nn -B2scale 2 -sigma 1379705753 3e6
GMP-ECM 6.2.1 [powered by GMP 4.2.4] [ECM]
Input number is 300581646694173102754989957730357512537506582488896855340284419687744533384371572427030444849066320698471799488342573090961576245101059 (135 digits)
Using B1=3000000, B2=11414255590, polynomial Dickson(12), sigma=1379705753
Step 1 took 18333ms
Step 2 took 15497ms
********** Factor found in step 2: 1331962064897051431769453993617935390404440387816273704654346513
Found composite factor of 64 digits: 1331962064897051431769453993617935390404440387816273704654346513
Probable prime cofactor 225668323907862446214856345291670054173175166345927281111241519005977043 has 72 digits
Exit 10
Interesting, huh?

P.S. C64 = P30 . P34 (this is not important)
Actually, it is important. Think about it.

Paul
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Old 2008-11-25, 12:42   #57
Batalov
 
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Rumack: You'd better tell the Captain we've got to land as soon as we can. This woman has to be gotten to a hospital.
Elaine Dickinson: A hospital? What is it?
Rumack: It's a big building with patients, but that's not important right now.
__________

I know what you mean, of course.
With Prime95 people (myself included) find 120+ digit "factors" every once in a while, with P-1, though... Same difference, sure.
For this to happen there must have been three factors (P<<1; the number was already cleared at 30-digits, and it's quite short, not Mersenne-size, therefore not much room), and two of them had to be smooth in the same field (let's say P~1/800 for 30-digits). Still, pretty lucky.

Last fiddled with by Batalov on 2008-11-25 at 13:01
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Old 2008-11-25, 13:38   #58
xilman
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Quote:
Originally Posted by Batalov View Post
I know what you mean, of course.
With Prime95 people (myself included) find 120+ digit "factors" every once in a while, with P-1, though... Same difference, sure.
For this to happen there must have been three factors (P<<1; the number was already cleared at 30-digits, and it's quite short, not Mersenne-size, therefore not much room), and two of them had to be smooth in the same field (let's say P~1/800 for 30-digits). Still, pretty lucky.
Sure, but nowhere near as lucky as finding a P64 with those parameters.

Paul
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Old 2008-11-25, 13:51   #59
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Quote:
Originally Posted by xilman View Post
Actually, it is important. Think about it.

Paul
http://www.snpp.com/episodes/2F17.html

Dr. S: Wait: did you know that there's a direct correlation between the
decline of Spirograph and the rise in gang activity? Think about
it.

Bart: I will. [walks off]
Dr. S: No you won't. [goes back to drawing]
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Old 2008-12-01, 01:02   #60
Jeff Gilchrist
 
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I think I just nabbed a big one...

I was factoring a C212, trying out yafu (so rho,p+1,p-1,ecm) and after a couple of minutes:
C212 = 11969 . 1541364950613953 . C193

Then doing a few minutes of P+1 on the C193 (playing with GMP-ECM 6.2.1), I ended up with:
C193 = P34 . P160

Code:
P34 = 4086525601957322196250605280513217 
P160 = 1116347430502685727295686258559284600000143009148663411245736927710476849533994789598158421658426637507289495130855789711863657445852880216696146697010516210753

Last fiddled with by Jeff Gilchrist on 2008-12-01 at 01:20
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Old 2008-12-03, 15:58   #61
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Another 160 digit prp co-factor found using GMP-ECM:

C188 = P28 . P160

Code:
C188 = 24282246583533357058956441317683022167750623010380385535734251894748038050513633364080896637485797011949098359363043063994158817112684635017983905521394893653678354661924887279901207289433
P28 = 6537366562602113177967158503
P160 = 3714377395087988869214434676837284949265028169225505688211061865951816791061201852303099504699959524370447330462435491495931668180505697643582022479048756165311
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Old 2008-12-03, 16:03   #62
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What were those numbers? Were they completely random?

Posts: 207.
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Old 2008-12-03, 16:08   #63
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Quote:
Originally Posted by 10metreh View Post
What were those numbers? Were they completely random?
The first was: 4^352+3^352
The second was a composite factor found while working on: 4^355+3^355

Jeff.
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Old 2008-12-03, 17:51   #64
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Quote:
Originally Posted by Jeff Gilchrist View Post
The first was: 4^352+3^352
The second was a composite factor found while working on: 4^355+3^355

Jeff.
Since there are still many unfactored composites within current table
limits, I must ask: why are you working on extending the limits?

Didn't you mother ever tell you: finish what you start before doing
something else???

Just my opinion.
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Old 2008-12-03, 19:04   #65
Jeff Gilchrist
 
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Quote:
Originally Posted by R.D. Silverman View Post
Since there are still many unfactored composites within current table limits, I must ask: why are you working on extending the limits?
When I first looked at the list, I just jumped to the bottom. I didn't realize there were still a lot of composites left. I will go back and look.

Quote:
Originally Posted by R.D. Silverman View Post
Didn't you mother ever tell you: finish what you start before doing something else???
Yes, but I didn't leave any composites unfinished, someone else should have listened to their mother. All the work I have done is complete.

Speaking of which 4^356+3^356 just gave me these after a few seconds of YAFU running rho:
4^356+3^356 (C215) = 337.329657. P207
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Old 2008-12-03, 20:11   #66
Batalov
 
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Jeff, the size of the last factor doesn't matter at all.
Please pay attention only to the size of the penultimate factor (or other things that do correlate with complexity).

Here's a couple of trivial examples of much larger last factors, just off the top of my head...
2^4973-3 = 2399 . 22993 . 147792832438060050225241 . p1467
10^2351+1 = 11 . 4703 . 307368548553345677 . 1080350324249483399506717 . p2305 (Primo-certified, just in case anyone was wondering)

Happy factoring! Welcome to the club.
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*these are not even my numbers

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