A120491 Numbers k such that 22*3^k + 1 is prime.

0, 1, 2, 4, 5, 10, 12, 14, 24, 34, 37, 52, 56, 65, 68, 96, 106, 128, 156, 169, 236, 254, 481, 618, 641, 672, 700, 774, 1274, 1625, 1841, 4650, 6030, 8372, 8760, 9173, 12776, 13873, 25214, 25548, 33834, 72005

Offset

1,3

Links

Table of n, a(n) for n=1..42.

Example

If k=96 then 22*3^k + 1 is a prime with 48 digits.

Mathematica

Select[Range[0, 2000], PrimeQ[22*3^# + 1] &] (* Stefan Steinerberger, Aug 06 2006 *)

Prog

(Magma) [ n: n in [0..3000] | IsPrime(22*3^n + 1) ]; // Vincenzo Librandi, Jan 31 2011
(PARI) is(n)=ispseudoprime(22*3^n+1) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Cf. A003306.

Sequence in context: A285697 A047611 A325095 * A177186 A375029 A260385

Adjacent sequences: A120488 A120489 A120490 * A120492 A120493 A120494

Keyword

nonn,more

Author

Parthasarathy Nambi, Aug 04 2006

Extensions

More terms from Stefan Steinerberger, Aug 06 2006

a(32)-a(41) from Michael S. Branicky, Jul 14 2023

a(42) from Michael S. Branicky, Oct 24 2024

Status

approved