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Old 2020-08-30, 10:23   #1607
LaurV
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Quote:
Originally Posted by James Heinrich View Post
Your "precious"...
Told you I'll bring luck if you put me on that list
This beauty popped up (62 digits, 202 bits):

Factor: 11357797528017579440065902285366253196028688791738880200930167 / (P-1, B1=1500000, B2=75000000)

Unfortunately, not prime, grrr... it would have been a nice "absolute ever" record. It splits into 122+81 bits, the larger of which is just a pinch smaller that my former record, and now I have two positions in top-300, (yay!), at 257 and 281. BloodIce, I come for you!

One odd thing worth mentioning: when I reported it, the server recorded it two times (once for each factor) and it gave me a double amount of credit (one full credit, for each factor).

Last fiddled with by LaurV on 2020-08-30 at 10:32 Reason: odd part
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Old 2020-08-30, 13:16   #1608
James Heinrich
 
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Quote:
Originally Posted by LaurV View Post
One odd thing worth mentioning: when I reported it, the server recorded it two times (once for each factor) and it gave me a double amount of credit (one full credit, for each factor).
It's a known thing. Once the server receives your factor it's checked and (if necessary) split into prime factors, and then processed as if you had submitted each prime factor separately. If both happen to be new factors then you get a "bonus". Consider it an incentive to find more composite factors.
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Old 2020-08-30, 16:30   #1609
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Quote:
Originally Posted by LaurV View Post
Factor: 11357797528017579440065902285366253196028688791738880200930167 / (P-1, B1=1500000, B2=75000000)...
Wow! That's big. How would you go about breaking this down into smaller factors, like "w = x * y * z?" I've seen this done before.
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Old 2020-08-30, 16:37   #1610
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Quote:
Originally Posted by storm5510 View Post
Wow! That's big. How would you go about breaking this down into smaller factors, like "w = x * y * z?" I've seen this done before.
Feed it to yafu, or msieve, or CADO; you know, any of the factoring programs used by other parts of this forum.

Try the "factoring" subforum for more info.
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Old 2020-08-30, 17:21   #1611
Uncwilly
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Quote:
Originally Posted by VBCurtis View Post
Feed it to yafu, or msieve, or CADO; you know, any of the factoring programs used by other parts of this forum.

Try the "factoring" subforum for more info.
or use https://www.alpertron.com.ar/ECM.HTM
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Old 2020-08-30, 17:23   #1612
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Quote:
Originally Posted by storm5510 View Post
Wow! That's big. How would you go about breaking this down into smaller factors, like "w = x * y * z?" I've seen this done before.
Dario Alpern has a good online factorization tool: https://www.alpertron.com.ar/ECM.HTM
(tool is online, calculations are done on your machine in the browser)

https://www.mersenne.ca/factor.php can also be used to factor small numbers (up to 45 digits, but also larger numbers that are Mersenne factors).

If you have YAFU installed, just open it and type factor(11357797528017579440065902285366253196028688791738880200930167) and you'll get your answer. This is what mersenne.ca does internally when it encounters a composite factor, and if it can't get the answer quickly (within a few seconds) then I can run that manually on my more-powerful home computer. Most numbers can be factored quickly, some can take forever (just ask M1277).
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Old 2020-09-01, 13:34   #1613
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Ryan found a 208 bit factor:
2137 has a factor 434527865148151913428610180914321766584011558417928142522774921


Last fiddled with by Uncwilly on 2020-09-01 at 13:35
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Old 2020-09-01, 14:34   #1614
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Quote:
Originally Posted by Uncwilly View Post
Ryan found a 208 bit factor:
2137 has a factor 434527865148151913428610180914321766584011558417928142522774921

My GPU could TF that in less than 4 times the age of the universe.
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Old 2020-09-01, 15:40   #1615
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Can I ask how long did the curve take? And would it be advisable to repeat one or two curves with the same bound to find similar sized other factor? ( atm the cofactor has been Prp'ed and show not prime).




edit: I realise it should have been a T65 curve, my apologies.

Last fiddled with by firejuggler on 2020-09-01 at 15:52
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Old 2020-09-01, 15:56   #1616
James Heinrich
 
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Quote:
Originally Posted by firejuggler View Post
Can I ask how long did the curve take?
By my calculations a single curve of those bounds should be in the order of 1-2 GHz-days. It's all the other curves that didn't find a factor that make it such a long/hard process.
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Old 2020-09-01, 19:27   #1617
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Quote:
Originally Posted by firejuggler View Post
Can I ask how long did the curve take? And would it be advisable to repeat one or two curves with the same bound to find similar sized other factor? ( atm the cofactor has been Prp'ed and show not prime).

edit: I realise it should have been a T65 curve, my apologies.
If you click on the exponent report linked in the post above yours, you'll see that B1 is 2.9G. That's T70 standard.

I don't think you understand ECM at all if you think an extra curve or two has any nontrivial probability to find another factor; never mind that there's no reason at all to think there's another one of the same size lurking just because one was found at this size.

Last fiddled with by VBCurtis on 2020-09-01 at 22:29 Reason: Last sentence: before --> because.
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