20150124, 23:02  #1 
Einyen
Dec 2003
Denmark
2·17·101 Posts 
P1/P+1 on Fermat numbers
Are there any records of how high P1 and P+1 have been taken on the "small" fermat numbers F12 to F26 ?

20150125, 03:08  #2 
Romulan Interpreter
"name field"
Jun 2011
Thailand
10,273 Posts 

20150125, 06:27  #3 
"Curtis"
Feb 2005
Riverside, CA
2^{2}·3·7·67 Posts 
Since P1 runs at nearly ten times the speed of an ECM curve with the same bounds, it always makes sense to do P1 for any candidate where ECM is useful. This relative speedup is why it is often suggested to do P1 with B1 ten times higher than the B1level of ECM effort.

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