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 A130815 Period 6: repeat [1, 5, 4, -1, -5, -4]. 6
 1, 5, 4, -1, -5, -4, 1, 5, 4, -1, -5, -4, 1, 5, 4, -1, -5, -4, 1, 5, 4, -1, -5, -4, 1, 5, 4, -1, -5, -4, 1, 5, 4, -1, -5, -4, 1, 5, 4, -1, -5, -4, 1, 5, 4, -1, -5, -4, 1, 5, 4, -1, -5, -4, 1, 5, 4, -1, -5, -4, 1, 5, 4, -1, -5, -4, 1, 5, 4, -1, -5, -4 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Continued fraction expansion of (5+sqrt(11))/7 = 1.1880892557650... - R. J. Mathar, Mar 08 2012 LINKS Index entries for linear recurrences with constant coefficients, signature (1,-1). FORMULA Also binomial transform of 1, 4, -5. a(n) = (1/6)*{-5*(n mod 6)-[(n+1) mod 6]+4*[(n+2) mod 6]+5*[(n+3) mod 6]+[(n+4) mod 6]-4*[(n+5) mod 6]}. - Paolo P. Lava, Aug 28 2007 From R. J. Mathar, Oct 30 2008: (Start) G.f.: (1+4x)/(1-x+x^2). a(n) = A010892(n) + 4*A010892(n-1). (End) From Wesley Ivan Hurt, Jun 17 2016: (Start) a(n) = a(n-1) - a(n-2) for n>1. a(n) = cos(n*Pi/3) + 3*sqrt(3)*sin(n*Pi/3). (End) MAPLE A130815:=n->cos(n*Pi/3)+3*sqrt(3)*sin(n*Pi/3): seq(A130815(n), n=0..100); # Wesley Ivan Hurt, Jun 17 2016 MATHEMATICA Flatten[Table[{1, 5, 4, -1, -5, -4}, {20}]] (* Wesley Ivan Hurt, Jun 17 2016 *) PadRight[{}, 120, {1, 5, 4, -1, -5, -4}] (* Harvey P. Dale, Jul 12 2020 *) PROG (PARI) a(n)=[1, 5, 4, -1, -5, -4][n%6+1] \\ Charles R Greathouse IV, Jun 02 2011 (MAGMA) &cat[[1, 5, 4, -1, -5, -4]: n in [0..20]]; // Wesley Ivan Hurt, Jun 17 2016 CROSSREFS Cf. A010892. Sequence in context: A198352 A113011 A028875 * A342797 A084129 A011503 Adjacent sequences:  A130812 A130813 A130814 * A130816 A130817 A130818 KEYWORD sign,easy,less AUTHOR Paul Curtz, Jul 16 2007 EXTENSIONS Edited by N. J. A. Sloane, Sep 15 2007 STATUS approved

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Last modified August 2 08:47 EDT 2021. Contains 346422 sequences. (Running on oeis4.)