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Old 2008-11-02, 18:02   #1
Joh14vers6
 
Nov 2008

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Default Unknown result P1-factoring with v25.7

After changing from v25.6 to v25.7 I got results like this with P1-factoring:
[Sun Nov 02 16:38:55 2008]
24737*2^16045687+1 completed P-1, B1=130000, B2=2200000, E=6, Wd1: 9F17E134

With v25.6 I got:
[Tue Oct 07 21:15:49 2008]
67607*2^15850467+1 completed P-1, B1=130000, B2=2200000, Wd1: 9A1AE89E

What means E=6?
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Old 2008-11-02, 20:13   #2
Prime95
P90 years forever!
 
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Aug 2002
Yeehaw, FL

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It refers to Suyama's (sp?) extension to P-1 stage 2 factoring. If enough memory is available, prime95 can choose an E value greater than 2 which gives it a slightly better chance of finding a factor in stage 2 (by finding some factors above the B2 value).

In short, don't worry about it
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Old 2008-11-02, 21:10   #3
Joh14vers6
 
Nov 2008

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Ok thanks for the explanation.

I putted some extra RAM in to speed up Stage 2 as well. That explains a lot.
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Old 2008-11-04, 06:21   #4
markr
 
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"Mark"
Feb 2003
Sydney

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Aha! That explains this recent result of mine:

Code:
P-1 found a factor in stage #2, B1=1000000, B2=40000000.
UID: markr/mr7, M820643 has a factor: 279780507749146102291903
If the exponent is p, and that factor is 2kp+1, then k is 170464201698635157, which factorises as
170464201698635157 = 3 x 5413 x 70297 x 149326579

Not that I check every one, but I hadn't seen a factor found by P-1 with one of k's factors > B2 before, so I was puzzled - until now.

Thanks!
Mark
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