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Numbers k such that 23*k^2 + 25 is prime.
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%I #15 Sep 08 2022 08:45:20

%S 6,18,36,42,48,66,108,126,174,198,204,216,234,246,252,312,342,372,402,

%T 426,504,516,546,564,582,618,624,642,666,702,708,732,768,774,822,852,

%U 888,906,924,936,948,966,972,978,984,996,1008,1014,1032,1062,1092,1098

%N Numbers k such that 23*k^2 + 25 is prime.

%H Emre Alkan, Alexandru Zaharescu, <a href="https://doi.org/10.1142/S1793042105000029">Nonvanishing of the Ramanujan tau function in short intervals</a>, International Journal of Number Theory, Vol. 1, No. 1 (2005) 45-51.

%e 23*198^2 + 25 = 901717 (prime).

%o (Magma) [ n: n in [0..1500] | IsPrime( 23*n^2 + 25) ] // _Vincenzo Librandi_, Jan 31 2011

%o (PARI) is(n)=isprime(23*n^2+25) \\ _Charles R Greathouse IV_, Jun 13 2017

%K nonn,easy

%O 1,1

%A _Parthasarathy Nambi_, Sep 26 2005

%E Edited by _Don Reble_, Nov 08 2005