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A002328
Numbers n such that n^2 - n - 1 is prime.
(Formerly M0494 N0179)
29
3, 4, 5, 6, 7, 9, 10, 11, 12, 14, 16, 17, 20, 21, 22, 25, 27, 29, 31, 32, 36, 39, 40, 42, 45, 46, 47, 49, 51, 54, 55, 56, 57, 60, 61, 65, 66, 67, 69, 71, 77, 84, 86, 87, 90, 94, 95, 97, 101, 102, 104, 115, 116, 121, 126, 127, 131, 132, 135, 139, 141, 142, 145, 146, 149
OFFSET
1,1
REFERENCES
D. H. Lehmer, Guide to Tables in the Theory of Numbers. Bulletin No. 105, National Research Council, Washington, DC, 1941, p. 46.
L. Poletti, Tavole di Numeri Primi Entro Limiti Diversi e Tavole Affini, Milan, 1920, p. 249.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
FORMULA
a(n) = (A088502(n)+1)/2. - Ray Chandler
a(n) = A094210(n) + 2. - R. J. Mathar, Aug 08 2012
MATHEMATICA
Select[Range[10^3], PrimeQ[#^2 - # - 1] &] (* Vincenzo Librandi, Mar 20 2014 *)
PROG
(Magma) [n: n in [1..300]|IsPrime(n^2-n-1)]; // Vincenzo Librandi, Nov 21 2010
(PARI) is(n)=isprime(n^2 - n - 1) \\ Charles R Greathouse IV, Apr 28 2015
CROSSREFS
KEYWORD
nonn,easy
EXTENSIONS
Extended by Ray Chandler, Sep 07 2005
STATUS
approved