A057910 Numbers k such that 2*3^k - 5 is prime.

2, 4, 6, 10, 12, 13, 19, 43, 48, 64, 72, 97, 187, 190, 336, 348, 676, 2484, 2719, 3298, 4726, 9901, 24466, 43980, 56302, 72175

Offset

1,1

Comments

a(24) > 37734. - Jinyuan Wang, Jan 20 2020

Links

Table of n, a(n) for n=1..26.

Mathematica

Do[ If[ PrimeQ[ 2*3^n - 5 ], Print[ n ] ], {n, 1, 2500} ]
Select[Range[10000], PrimeQ[2*3^#-5]&] (* Harvey P. Dale, Jan 19 2018 *)

Prog

(PARI) is(n)=ispseudoprime(2*3^n-5) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Cf. A057911 (2*3^k + 5 is prime).

Sequence in context: A226295 A090127 A388841 * A387335 A336066 A120351

Adjacent sequences: A057907 A057908 A057909 * A057911 A057912 A057913

Keyword

nonn,more

Author

Robert G. Wilson v, Nov 16 2000

Extensions

a(23) from Jinyuan Wang, Jan 20 2020

a(24)-a(26) from Michael S. Branicky, Jul 09 2024

Status

approved