A133467 - OEIS

A133467

a(n) = a(n-1) + 6*a(n-2) for n >= 2, a(0)=1, a(1)=2.

1, 2, 8, 20, 68, 188, 596, 1724, 5300, 15644, 47444, 141308, 425972, 1273820, 3829652, 11472572, 34450484, 103285916, 309988820, 929704316, 2789637236, 8367863132, 25105686548, 75312865340, 225946984628, 677824176668

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OFFSET

0,2

LINKS

Harvey P. Dale, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (1,6).

FORMULA

G.f.: (1+x)/((1+2*x)*(1-3*x)).

a(n) = Sum_{k=0..n+1} A122950(n+1,k)*5^(n+1-k). - Philippe Deléham, Jan 08 2008

MAPLE

Digits := 50:

for n from 0 to 40 do round(.8*3^n+.2*(-2)^n) end do;

# Matt C. Anderson, Jul 18 2017

MATHEMATICA

LinearRecurrence[{1, 6}, {1, 2}, 30] (* Harvey P. Dale, Apr 05 2014 *)

PROG

(Sage) from sage.combinat.sloane_functions import recur_gen2b; it = recur_gen2b(1, 2, 1, 6, lambda n: 0); [next(it) for i in range(0, 29)] # Zerinvary Lajos, Jul 03 2008

CROSSREFS

Sequence in context: A081157 A099177 A100097 * A091004 A005559 A001471

Adjacent sequences: A133464 A133465 A133466 * A133468 A133469 A133470

KEYWORD

easy,nonn

AUTHOR

Philippe Deléham, Jan 03 2008

STATUS

approved