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A002971
Numbers k such that 4*k^2 + 25 is prime.
(Formerly M0587)
2
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
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
KEYWORD
nonn,easy
STATUS
approved