0,6

2^(2^n) + 1 belongs to A019434 if and only if a(n) = 0.

Table of n, a(n) for n=0..8.

Wikipedia, Fermat number

Cf. A000215, A242620.

Sequence in context: A223466 A281658 A234304 * A224619 A186060 A253866

Adjacent sequences: A242616 A242617 A242618 * A242620 A242621 A242622

nonn

Arkadiusz Wesolowski, May 19 2014

approved