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A130567 Expansion of x*(2 - 7*x + 2*x^2)/((1-x)*(1-4*x)*(1-2*x)). 0
2, 7, 23, 79, 287, 1087, 4223, 16639, 66047, 263167, 1050623, 4198399, 16785407, 67125247, 268468223, 1073807359, 4295098367, 17180131327, 68720001023, 274878955519, 1099513724927, 4398050705407, 17592194433023, 70368760954879 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..24.

A. M. Cohen and D. E. Taylor, On a Certain Lie Algebra Defined by a Finite Group, American Math Monthly, volume 114, Number 7, Aug-Sept 2007, pages 633-638.

FORMULA

a(n) = 2^(2*n - 1) + 2*a(n - 1) + 1.

From R. J. Mathar, Jun 13 2008: (Start)

O.g.f.: x*(2 - 7*x + 2*x^2)/((1-x)*(1-4*x)*(1-2*x)).

a(n) = A093069(n-2), n>1. (End)

a(n) = -1 + 2*2^n + 4^n, with n>=0. - Paolo P. Lava, Jul 30 2008

MATHEMATICA

f[n_Integer?Positive] := f[n] = 2^(2*n - 1) + 2*f[n - 1] + 1; f[0] = 2; Table[f[n], {n, 0, 30}]

CROSSREFS

Cf. A099393, A028244.

Sequence in context: A198944 A112657 A007717 * A091514 A143629 A176287

Adjacent sequences:  A130564 A130565 A130566 * A130568 A130569 A130570

KEYWORD

nonn,easy

AUTHOR

Roger L. Bagula, Aug 09 2007

EXTENSIONS

New name from Joerg Arndt, Feb 08 2015

STATUS

approved

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Last modified February 28 21:56 EST 2015. Contains 255095 sequences.