1,2

Odd terms are of the form Product_{0<=i<=m} F_i, 0<=m<=4, where F_i is a Fermat prime 2^(2^i)+1

a(7)=3*5*17*257

Cf. A047994.

Sequence in context: A003505 A120601 A145272 this_sequence A126453 A007081 A126455

Adjacent sequences: A117817 A117818 A117819 this_sequence A117821 A117822 A117823

nonn

Yasutoshi Kohmoto zbi74583(AT)boat.zero.ad.jp, Apr 30 2006