A077991 Expansion of 1/(1+2*x+2*x^2-2*x^3).

1, -2, 2, 2, -12, 24, -20, -32, 152, -280, 192, 480, -1904, 3232, -1696, -6880, 23616, -36864, 12736, 95488, -290176, 414848, -58368, -1293312, 3533056, -4596224, -460288, 17179136, -42630144, 49981440, 19655680, -224534528, 509720576, -531060736, -406388736, 2894340096, -6038024192

Offset

0,2

Links

G. C. Greubel, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (-2,-2,2).

Formula

a(n) = (-1)^n * A077945(n). - G. C. Greubel, Jun 26 2019

Mathematica

LinearRecurrence[{-2, -2, 2}, {1, -2, 2}, 40] (* or *) CoefficientList[ Series[1/(1+2*x+2*x^2-2*x^3), {x, 40, 40}], x] (* G. C. Greubel, Jun 26 2019 *)

Prog

(PARI) Vec(1/(1+2*x+2*x^2-2*x^3)+O(x^40)) \\ Charles R Greathouse IV, Sep 27 2012
(Magma) R<x>:=PowerSeriesRing(Integers(), 40); Coefficients(R!( 1/(1+2*x+2*x^2-2*x^3) )); // G. C. Greubel, Jun 26 2019
(Sage) (1/(1+2*x+2*x^2-2*x^3)).series(x, 40).coefficients(x, sparse=False) # G. C. Greubel, Jun 26 2019
(GAP) a:=[1, -2, 2];; for n in [4..40] do a[n]:=-2*(a[n-1]+a[n-2]-a[n-3]); od; a; # G. C. Greubel, Jun 26 2019

Crossrefs

Cf. A077945.

Sequence in context: A135322 A106541 A077945 * A336491 A049148 A369077

Adjacent sequences: A077988 A077989 A077990 * A077992 A077993 A077994

Keyword

sign,easy

Author

N. J. A. Sloane, Nov 17 2002

Status

approved