A002971 Numbers k such that 4*k^2 + 25 is prime. (Formerly M0587)

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, 53, 54, 56, 62, 63, 66, 67, 68, 69, 73, 74, 77, 79, 82, 83, 91, 99, 101, 102, 103, 107, 108, 114, 116, 118, 122, 131, 134, 141, 142, 147, 148, 151, 154, 156, 157, 158, 159, 164

Offset

1,2

References

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

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

Links

T. D. Noe, Table of n, a(n) for n = 1..1000

E. Kogbetliantz and A. Krikorian Handbook of First Complex Prime Numbers, Gordon and Breach, NY, 1971 [Annotated scans of a few pages]

Mathematica

Select[Range[200], PrimeQ[4 #^2 + 25] &] (* Vincenzo Librandi, Mar 19 2014 *)

Prog

(Magma) [n: n in [0..600] |IsPrime(4*n^2+25)]; // Vincenzo Librandi, Nov 21 2010
(PARI) is(n)=isprime(4*n^2+25) \\ Charles R Greathouse IV, Jun 06 2017

Crossrefs

Sequence in context: A117847 A045577 A111020 * A157318 A158031 A139461

Adjacent sequences: A002968 A002969 A002970 * A002972 A002973 A002974

Keyword

nonn,easy

Author

N. J. A. Sloane

Status

approved