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Old 2005-05-27, 17:23   #1
[Leo_01]
 
May 2005
Lyon

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Default A question about ecm's top100 (novice)

Hello,

I found this factor:

Run 12 out of 940:
Using B1=1000000, B2=839549779, polynomial Dickson(3), sigma=3995282753
Step 1 took 77500ms
Step 2 took 38490ms
********** Factor found in step 2: 71714208610579105792540408011003007751948902382471874795499986007319
Found composite factor of 68 digits: 71714208610579105792540408011003007751948902382471874795499986007319
Composite cofactor 6587259828147373028882426117244546464250110605851985519710308763002069923 has 73 digits

It's a factor of p20005 and is composite :-(.
The ECMNET project maintained a list of all the factors found with GMP-ECM.
But is it necessary that this factor is prime? or any factor found with GMP-ECM (composite or prime) is valid?

Thanks you in advance.
Alex


Sorry for my bad english.
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Old 2005-05-27, 17:33   #2
VJS
 
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Dec 2004

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Yes it has to be a prime factor.
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Old 2005-05-27, 17:38   #3
ET_
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"Luigi"
Aug 2002
Team Italia

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Quote:
Originally Posted by [Leo_01]
Found composite factor of 68 digits: 71714208610579105792540408011003007751948902382471874795499986007319
Composite cofactor 6587259828147373028882426117244546464250110605851985519710308763002069923 has 73 digits
Composite factor of 68 digits splits as
221327431219133172774525501130163 * 324018619000623911696302737119750413

while composite cofactor of 73 digits splits as
28242483789997587424530225403013 * 233239394846721295985738738334629297112071

Luigi
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Old 2005-05-27, 18:03   #4
[Leo_01]
 
May 2005
Lyon

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thank you :-)
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