A114272 Numbers k such that k^2 + 9 is prime.

2, 8, 10, 20, 32, 38, 40, 52, 58, 62, 70, 82, 88, 98, 100, 110, 112, 118, 140, 142, 160, 170, 188, 190, 200, 202, 212, 218, 220, 242, 298, 308, 320, 332, 350, 358, 368, 380, 382, 400, 410, 412, 422, 448, 472, 482, 490, 502, 512, 530, 538, 542, 568, 572, 578

Offset: 1

Author

Zak Seidov, Nov 19 2005

Keywords

• nonn

Links

• G. C. Greubel, Table of n, a(n) for n = 1..1000

Crossrefs

Other sequences of the type "Numbers k such that k^2 + i is prime": A005574 (i=1), A067201 (i=2), A049422 (i=3), A007591 (i=4), A078402 (i=5), A114269 (i=6), A114270 (i=7), A114271 (i=8), this sequence (i=9), A114273 (i=10), A114274 (i=11), A114275 (i=12).

Programs

Mathematica

lst={};Do[If[PrimeQ[n^2+9], AppendTo[lst, n]], {n, 600}];lst (* Vladimir Joseph Stephan Orlovsky, Aug 26 2008 *)
Select[Range[2,600,2],PrimeQ[#^2+9]&] (* Harvey P. Dale, Feb 28 2023 *)

PARI

is(n)=isprime(n^2+9) \\ Charles R Greathouse IV, Feb 17 2017

Formula

a(n) = 2 * A002970(n). - Michel Marcus, Jan 20 2015