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Numbers k such that k^2 + 8 is prime.
16

%I #17 Aug 27 2023 15:27:58

%S 3,9,15,21,33,51,57,81,87,111,117,123,129,135,141,147,153,177,189,213,

%T 219,255,279,285,315,321,327,345,351,363,399,417,465,471,477,483,495,

%U 549,579,585,627,657,663,669,723,735,741,747,759,771,783,789,807,825

%N Numbers k such that k^2 + 8 is prime.

%H G. C. Greubel, <a href="/A114271/b114271.txt">Table of n, a(n) for n = 1..1000</a>

%t a={};Do[If[PrimeQ[n^2+8], AppendTo[a, n]], {n,0,10^3}]; a (* _Vladimir Joseph Stephan Orlovsky_, Apr 29 2008 *)

%t Select[Range[1,901,2],PrimeQ[#^2+8]&] (* _Harvey P. Dale_, Aug 27 2023 *)

%o (PARI) is(n)=isprime(n^2+8) \\ _Charles R Greathouse IV_, Jan 21 2015

%Y 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), this sequence (i=8), A114272 (i=9), A114273 (i=10), A114274 (i=11), A114275 (i=12).

%K nonn

%O 1,1

%A _Zak Seidov_, Nov 19 2005