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Numbers n such that 23*n^2 - 9 is prime.
1

%I #8 Jun 12 2017 19:22:14

%S 2,4,16,38,40,44,70,82,86,88,116,128,130,142,152,158,170,178,194,224,

%T 226,238,262,268,298,304,310,320,346,352,362,364,368,392,406,418,434,

%U 446,452,458,460,472,478,490,494

%N Numbers n such that 23*n^2 - 9 is prime.

%e If n=88 then 23*n^2 - 9 = 178103 (prime).

%t Select[Range[500], PrimeQ[(23#^2 - 9)] &] (* _Stefan Steinerberger_, Feb 28 2006 *)

%o (PARI) is(n)=isprime(23*n^2-9) \\ _Charles R Greathouse IV_, Jun 12 2017

%K nonn,easy

%O 1,1

%A _Parthasarathy Nambi_, Sep 30 2005

%E More terms from _Stefan Steinerberger_, Feb 28 2006