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Numbers n such that 23*n^2 - 49 is prime.
1

%I #15 Sep 08 2022 08:45:20

%S 2,8,10,16,20,22,34,36,46,52,58,68,72,74,78,80,102,104,122,130,132,

%T 134,148,152,156,162,164,166,186,198,200,204,208,212,214,250,254,264,

%U 270,278,284,302,318,320,328,332,338,340,358,362,366,380,382,390,396,440

%N Numbers n such that 23*n^2 - 49 is prime.

%C All the numbers in this sequence are even.

%H G. C. Greubel, <a href="/A110913/b110913.txt">Table of n, a(n) for n = 1..5000</a>

%e If n=80 then(23*n^2) - 49 = 147151 (prime).

%t Select[Range[700], PrimeQ[23*#^2 - 49] &] (* _G. C. Greubel_, Oct 19 2017 *)

%o (Magma) [n: n in [2..100000] |IsPrime((23*n^2)-49)] - _Vincenzo Librandi_, Nov 13 2010

%o (PARI) is(n)=isprime(23*n^2-49) \\ _Charles R Greathouse IV_, Jun 13 2017

%K nonn,easy

%O 1,1

%A _Parthasarathy Nambi_, Oct 03 2005