A058960 Numbers k such that (3^k + 5)/2 is prime.

0, 2, 4, 6, 10, 60, 66, 100, 144, 156, 450, 454, 456, 744, 1354, 1942, 2074, 2556, 3252, 4300, 9148, 10318, 10806, 19518, 26182, 83580

Offset

1,2

Links

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

Mathematica

Do[ If[ PrimeQ[(3^n + 5) / 2], Print[n] ], {n, 0, 3000} ]
Select[Range[0, 10000], PrimeQ[(3^# + 5)/2] &] (* Vincenzo Librandi, Sep 29 2012 *)

Prog

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

Crossrefs

Sequence in context: A207667 A085809 A073308 * A036053 A237816 A088906

Adjacent sequences: A058957 A058958 A058959 * A058961 A058962 A058963

Keyword

nonn,more

Author

Robert G. Wilson v, Jan 13 2001

Extensions

Added a(1)=0 and a(19)-a(21) from Vincenzo Librandi, Sep 29 2012

a(22)-a(24) from Jinyuan Wang, Jan 27 2020

a(25) from Michael S. Branicky, Apr 24 2023

a(26) from Michael S. Branicky, Oct 17 2024

Status

approved