A111974 - OEIS

A111974

Primes of the form 2*3^k + 1.

3, 7, 19, 163, 487, 1459, 39367, 86093443, 258280327, 411782264189299, 116299474006080119380780339, 3140085798164163223281069127, 84782316550432407028588866403, 20602102921755074907947094535687, 1910009901593650473786381403548828023839870277948686259673707683

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OFFSET

1,1

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..23

Hartosh Singh Bal and Gaurav Bhatnagar, Prime number conjectures from the Shapiro class structure, arXiv:1903.09619 [math.NT], 2019-2020.

FORMULA

a(n) = A052919(A003306(n)+1). - Amiram Eldar, Jul 18 2025

MATHEMATICA

Select[2*3^Range[100]+1, PrimeQ]

CROSSREFS

Cf. A003306 (k such that 2*3^k + 1 is prime), A003307 (k such that 2*3^k - 1 is prime), A052919.

Sequence in context: A245723 A118128 A113875 * A243100 A173400 A281971

Adjacent sequences: A111971 A111972 A111973 * A111975 A111976 A111977

KEYWORD

nonn

AUTHOR

T. D. Noe, Aug 24 2005

EXTENSIONS

a(15) from Amiram Eldar, Jul 18 2025

STATUS

approved