A077992 Expansion of 1/(1+2*x+2*x^2-x^3).

1, -2, 2, 1, -8, 16, -15, -10, 66, -127, 112, 96, -543, 1006, -830, -895, 4456, -7952, 6097, 8166, -36478, 62721, -44320, -73280, 297921, -493602, 318082, 648961, -2427688, 3875536, -2246735, -5685290, 19739586, -30355327, 15546192, 49357856, -160163423, 237157326, -104629950

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,-2,1).

Formula

a(n) = (-1)^n*A077944(n).

Mathematica

CoefficientList[Series[1/(1+2x+2x^2-x^3), {x, 0, 40}], x] (* or *) LinearRecurrence[ {-2, -2, 1}, {1, -2, 2}, 40] (* Harvey P. Dale, Aug 17 2017 *)

Prog

(PARI) my(x='x+O('x^40)); Vec(1/(1+2*x+2*x^2-x^3)) \\ G. C. Greubel, Jun 26 2019
(Magma) R<x>:=PowerSeriesRing(Integers(), 40); Coefficients(R!( 1/(1+2*x+2*x^2-x^3) )); // G. C. Greubel, Jun 26 2019
(Sage) (1/(1+2*x+2*x^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]-2*a[n-2]+a[n-3]; od; a; # G. C. Greubel, Jun 26 2019

Crossrefs

Cf. A077944.

Sequence in context: A238182 A117260 A077944 * A126586 A128463 A136730

Adjacent sequences: A077989 A077990 A077991 * A077993 A077994 A077995

Keyword

sign

Author

N. J. A. Sloane, Nov 17 2002

Status

approved