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A154627 Expansion of (1-5x)/(1-8x+4x^2). 1
1, 3, 20, 148, 1104, 8240, 61504, 459072, 3426560, 25576192, 190903296, 1424921600, 10635759616, 79386390528, 592548085760, 4422839123968, 33012520648704, 246408808693760, 1839220386955264, 13728127860867072 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Hankel transform of 1,1,4,18,88,.... (see A081671).

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) = 8*a(n-1) - 4*a(n-2), n > 1; a(0)=1, a(1)=3. [Philippe Deléham, Feb 02 2009]

a(n) = (1/2)*((4-2*sqrt(3))^n + (4+2*sqrt(3))^n) + (1/12)*sqrt(3)*((4-2*sqrt(3))^n -(4+2*sqrt(3))^n), with n >= 0. [Paolo P. Lava, Feb 13 2009]

MAPLE

A[0]:= 1: A[1]:= 3:

for n from 2 to 100 do A[n]:= 8*A[n-1]-4*A[n-2] od:

seq(A[n], n=0..100); # Robert Israel, Aug 10 2014

MATHEMATICA

LinearRecurrence[{8, -4}, {1, 3}, 20] (* Harvey P. Dale, Aug 10 2014 *)

CoefficientList[Series[(1 - 5 x)/(1 - 8 x + 4 x^2), {x, 0, 50}], x] (* Vincenzo Librandi, Aug 10 2014 *)

PROG

(PARI) Vec((1-5*x)/(1-8*x+4*x^2)+O(x^50)) \\ Michel Marcus, Aug 10 2014

CROSSREFS

Sequence in context: A068571 A074569 A026303 * A320350 A091172 A091168

Adjacent sequences:  A154624 A154625 A154626 * A154628 A154629 A154630

KEYWORD

easy,nonn

AUTHOR

Paul Barry, Jan 13 2009

STATUS

approved

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Last modified April 5 06:13 EDT 2020. Contains 333238 sequences. (Running on oeis4.)