A119573 Primes that have one of the forms 2^(2^n) + 1, 2^(2^n - 1) + 2^(2^(n + 1) - 1) + 1 or (2^(2^n) + 1 + 2^(2^(n + 1) - 1) + 1)/2.

3, 5, 7, 11, 17, 73, 137, 257, 65537

Offset

1,1

Links

Table of n, a(n) for n=1..9.

Mathematica

a = Union[Flatten[Table[{2^(2^n) + 1, 2^(2^n - 1) + 2^(2^(n + 1) - 1) + 1, (2^(2^n) + 1 + 2^(2^(n + 1) - 1) + 1)/2}, {n, 0, 10}]]] aout = Flatten[Table[If[PrimeQ[a[[n]]], a[[n]], {}], {n, 1, Length[a]}]]

Crossrefs

Cf. A019434.

Sequence in context: A356751 A038944 A124081 * A001366 A093329 A246533

Adjacent sequences: A119570 A119571 A119572 * A119574 A119575 A119576

Keyword

nonn

Author

Roger L. Bagula, May 31 2006

Extensions

Edited by N. J. A. Sloane, Jun 03 2006

Status

approved