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Numbers n such that 5*n^2 + 9 is prime.
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%I #9 Jun 13 2017 12:40:52

%S 2,4,10,16,26,28,38,40,44,46,58,70,80,82,88,94,98,110,116,128,130,136,

%T 140,142,154,164,178,194,200,208,212,214,220,224,236,248,250,254,256,

%U 268,278,284,298,310,320,322,332,334,338,362,392,406,422,424,458,460

%N Numbers n such that 5*n^2 + 9 is prime.

%e If n=154 then 5*n^2 + 9 = 118589 (prime).

%t Select[Range[500], PrimeQ[5*#^2 + 9] &] (* _Stefan Steinerberger_, Feb 26 2006 *)

%o (PARI) is(n)=isprime(5*n^2+9) \\ _Charles R Greathouse IV_, Jun 13 2017

%K nonn,easy

%O 1,1

%A _Parthasarathy Nambi_, Oct 18 2005

%E More terms from _Stefan Steinerberger_, Feb 26 2006