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A002328 Numbers n such that n^2 - n - 1 is prime.
(Formerly M0494 N0179)
28
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 (list; graph; refs; listen; history; text; internal format)
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

Carmine Suriano, Table of n, a(n) for n = 1..60000

FORMULA

a(n) = (A088502(n)+1)/2. - Ray Chandler

a(n) = A094210(n)+2. - R. J. Mathar, Aug 08 2012

MATHEMATICA

lst={}; Do[If[PrimeQ[n^2-n-1], AppendTo[lst, n]], {n, 10^5}]; lst (* Vladimir Joseph Stephan Orlovsky, Aug 21 2008 *)

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

Cf. A002327, A088502, A110013.

Sequence in context: A247914 A184518 A288228 * A039133 A113777 A285659

Adjacent sequences:  A002325 A002326 A002327 * A002329 A002330 A002331

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane

EXTENSIONS

Extended by Ray Chandler, Sep 07 2005

STATUS

approved

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Last modified September 24 04:14 EDT 2017. Contains 292402 sequences.