A138083 Numbers n such that (3^(2^n) + 1)/2 is prime.

0, 1, 2, 4, 5, 6

Offset

1,3

Comments

See A171381, which is the main entry for this sequence.

Links

Table of n, a(n) for n=1..6.

Prog

(PARI) is(n)=ispseudoprime((3^(2^n)+1)/2) \\ Charles R Greathouse IV, Jun 06 2017

Crossrefs

Cf. A093625, A171381.

Sequence in context: A327326 A170882 A116680 * A181524 A240568 A309681

Adjacent sequences: A138080 A138081 A138082 * A138084 A138085 A138086

Keyword

nonn,more,hard

Author

N. J. A. Sloane, Dec 09 2009

Status

approved