A111149 Numbers k such that 5*k^2 + 9 is prime.

2, 4, 10, 16, 26, 28, 38, 40, 44, 46, 58, 70, 80, 82, 88, 94, 98, 110, 116, 128, 130, 136, 140, 142, 154, 164, 178, 194, 200, 208, 212, 214, 220, 224, 236, 248, 250, 254, 256, 268, 278, 284, 298, 310, 320, 322, 332, 334, 338, 362, 392, 406, 422, 424, 458, 460

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Example

If k=154 then 5*k^2 + 9 = 118589 (prime).

Maple

select(k -> isprime(5*k ^2+ 9), [seq(k, k=0..1000, 2)]); # Robert Israel, Aug 18 2025

Mathematica

Select[Range[500], PrimeQ[5*#^2 + 9] &] (* Stefan Steinerberger, Feb 26 2006 *)

Prog

(PARI) is(n)=isprime(5*n^2+9) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Sequence in context: A039682 A218665 A189558 * A123689 A137928 A293154

Adjacent sequences: A111146 A111147 A111148 * A111150 A111151 A111152

Keyword

nonn,easy

Author

Parthasarathy Nambi, Oct 18 2005

Extensions

More terms from Stefan Steinerberger, Feb 26 2006

Status

approved