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A138083 Numbers n such that (3^(2^n) + 1)/2 is prime. 2
0, 1, 2, 4, 5, 6 (list; graph; refs; listen; history; text; internal format)
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: A026404 A170882 A116680 * A181524 A240568 A287224

Adjacent sequences:  A138080 A138081 A138082 * A138084 A138085 A138086

KEYWORD

nonn,more,hard

AUTHOR

N. J. A. Sloane, Dec 09 2009

STATUS

approved

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Last modified August 21 21:36 EDT 2017. Contains 290908 sequences.