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A032124 "BIK" (reversible, indistinct, unlabeled) transform of 2,2,2,2... 1
2, 5, 12, 33, 90, 261, 756, 2241, 6642, 19845, 59292, 177633, 532170, 1595781, 4785156, 14353281, 43053282, 129153285, 387440172, 1162300833, 3486843450, 10460471301, 31381236756, 94143533121, 282430067922, 847289672325, 2541867422652, 7625600673633 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

C. G. Bower, Transforms (2)

Index entries for linear recurrences with constant coefficients, signature (3,3,-9).

FORMULA

a(n) = (1/6)*((5-(-1)^n)*3^floor(n/2) + 2*3^n). - Ralf Stephan, May 11 2004

a(n) = 3*a(n-1)+3*a(n-2)-9*a(n-3). G.f.: -x*(9*x^2+x-2) / ((3*x-1)*(3*x^2-1)). - Colin Barker, Dec 15 2012

MATHEMATICA

CoefficientList[Series[-(9 x^2 + x - 2)/((3 x - 1) (3 x^2 - 1)), {x, 0, 30}], x] (* Vincenzo Librandi, Oct 19 2013 *)

PROG

(MAGMA) [(1/6)*((5-(-1)^n)*3^Floor(n/2) + 2*3^n): n in [1..30]]; // Vincenzo Librandi, Oct 19 2013

CROSSREFS

Sequence in context: A292212 A212823 A292213 * A292214 A292215 A292216

Adjacent sequences:  A032121 A032122 A032123 * A032125 A032126 A032127

KEYWORD

nonn,easy

AUTHOR

Christian G. Bower

EXTENSIONS

More terms from Vincenzo Librandi, Oct 19 2013

STATUS

approved

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Last modified February 23 09:18 EST 2018. Contains 299490 sequences. (Running on oeis4.)