P-1/P+1 on Fermat numbers

[ATH]

Are there any records of how high P-1 and P+1 have been taken on the "small" fermat numbers F12 to F26 ?

[LaurV]

Originally Posted by ATH

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)

[VBCurtis]

Originally Posted by LaurV

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.