A002971 - OEIS

%I M0587 #29 Oct 20 2023 22:00:27

%S 1,2,3,4,8,9,11,12,13,14,16,17,18,21,23,26,29,34,36,37,38,47,48,49,51,

%T 53,54,56,62,63,66,67,68,69,73,74,77,79,82,83,91,99,101,102,103,107,

%U 108,114,116,118,122,131,134,141,142,147,148,151,154,156,157,158,159,164

%N Numbers k such that 4*k^2 + 25 is prime.

%D E. Kogbetliantz and A. Krikorian, Handbook of First Complex Prime Numbers, Gordon and Breach, NY, 1971, p. 1.

%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

%H T. D. Noe, <a href="/A002971/b002971.txt">Table of n, a(n) for n = 1..1000</a>

%H E. Kogbetliantz and A. Krikorian <a href="/A002970/a002970.pdf">Handbook of First Complex Prime Numbers</a>, Gordon and Breach, NY, 1971 [Annotated scans of a few pages]

%t Select[Range[200], PrimeQ[4 #^2 + 25] &] (* _Vincenzo Librandi_, Mar 19 2014 *)

%o (Magma) [n: n in [0..600] |IsPrime(4*n^2+25)]; // _Vincenzo Librandi_, Nov 21 2010

%o (PARI) is(n)=isprime(4*n^2+25) \\ _Charles R Greathouse IV_, Jun 06 2017

%K nonn,easy

%O 1,2

%A _N. J. A. Sloane_