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A190510 a(n) = 8*a(n-1) + 4*a(n-2), with a(0)=0, a(1)=1. 4
0, 1, 8, 68, 576, 4880, 41344, 350272, 2967552, 25141504, 213002240, 1804583936, 15288680448, 129527779328, 1097376956416, 9297126768640, 78766521974784, 667320682872832, 5653631550881792, 47898335138545664, 405801207311892480, 3438002999049322496 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (8,4).

FORMULA

a(n) = (1/20)*sqrt(5)*((4+2*sqrt(5))^n-(4-2*sqrt(5))^n). - Paolo P. Lava, Jun 01 2011

G.f.: x/(1 - 8*x - 4*x^2). - R. J. Mathar, Nov 21 2011

a(n+1) = Sum_{k, 0<=k<=n} A099089(n,k)*4^k. - Philippe Deléham, Nov 21 2011

MATHEMATICA

LinearRecurrence[{8, 4}, {0, 1}, 50]

PROG

(Magma) I:=[0, 1]; [n le 2 select I[n] else 8*Self(n-1)+4*Self(n-2): n in [1..20]]; // Vincenzo Librandi, Nov 23 2011

(PARI) x='x+O('x^30); concat([0], Vec(x/(1-8*x-4*x^2))) \\ G. C. Greubel, Jan 24 2018

CROSSREFS

Sequence in context: A296670 A263477 A249390 * A282563 A163307 A281337

Adjacent sequences:  A190507 A190508 A190509 * A190511 A190512 A190513

KEYWORD

nonn,easy

AUTHOR

Vladimir Joseph Stephan Orlovsky, May 24 2011

STATUS

approved

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Last modified October 7 04:30 EDT 2022. Contains 357270 sequences. (Running on oeis4.)