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Old 2015-01-24, 23:02   #1
ATH
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Default P-1/P+1 on Fermat numbers

Are there any records of how high P-1 and P+1 have been taken on the "small" fermat numbers F12 to F26 ?
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Old 2015-01-25, 03:08   #2
LaurV
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Quote:
Originally Posted by ATH View Post
Are there any records of how high P-1 and P+1 have been taken on the "small" fermat numbers F12 to F26 ?
Does it make sense, considering the huge qty of ECM done? (it is not rhetoric, it is a sincere question)
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Old 2015-01-25, 06:27   #3
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Originally Posted by LaurV View Post
Does it make sense, considering the huge qty of ECM done? (it is not rhetoric, it is a sincere question)
Since P-1 runs at nearly ten times the speed of an ECM curve with the same bounds, it always makes sense to do P-1 for any candidate where ECM is useful. This relative speedup is why it is often suggested to do P-1 with B1 ten times higher than the B1-level of ECM effort.
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