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2008-11-25, 12:10   #56
xilman
Bamboozled!

"𒉺𒌌𒇷𒆷𒀭"
May 2003
Down not across

2·5,323 Posts

Quote:
 Originally Posted by Batalov (32·10^145+13)/9 = 355..557 = 37 · 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

 2008-11-25, 12:42 #57 Batalov     "Serge" Mar 2008 Phi(4,2^7658614+1)/2 222568 Posts 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
2008-11-25, 13:38   #58
xilman
Bamboozled!

"𒉺𒌌𒇷𒆷𒀭"
May 2003
Down not across

2×5,323 Posts

Quote:
 Originally Posted by Batalov 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

2008-11-25, 13:51   #59
ATH
Einyen

Dec 2003
Denmark

17·181 Posts

Quote:
 Originally Posted by xilman 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]

 2008-12-01, 01:02 #60 Jeff Gilchrist     Jun 2003 Ottawa, Canada 49416 Posts 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
 2008-12-03, 15:58 #61 Jeff Gilchrist     Jun 2003 Ottawa, Canada 22·293 Posts Another 160 digit prp co-factor found using GMP-ECM: C188 = P28 . P160 Code: C188 = 24282246583533357058956441317683022167750623010380385535734251894748038050513633364080896637485797011949098359363043063994158817112684635017983905521394893653678354661924887279901207289433 P28 = 6537366562602113177967158503 P160 = 3714377395087988869214434676837284949265028169225505688211061865951816791061201852303099504699959524370447330462435491495931668180505697643582022479048756165311
 2008-12-03, 16:03 #62 10metreh     Nov 2008 91216 Posts What were those numbers? Were they completely random? Posts: 207.
2008-12-03, 16:08   #63
Jeff Gilchrist

Jun 2003

117210 Posts

Quote:
 Originally Posted by 10metreh 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.

2008-12-03, 17:51   #64
R.D. Silverman

Nov 2003

1D2416 Posts

Quote:
 Originally Posted by Jeff Gilchrist 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.

2008-12-03, 19:04   #65
Jeff Gilchrist

Jun 2003

22248 Posts

Quote:
 Originally Posted by R.D. Silverman 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 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

 2008-12-03, 20:11 #66 Batalov     "Serge" Mar 2008 Phi(4,2^7658614+1)/2 24AE16 Posts 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. ___ *these are not even my numbers

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