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A077990 Expansion of 1/(1+2*x+x^2-x^3). 2
1, -2, 3, -3, 1, 4, -12, 21, -26, 19, 9, -63, 136, -200, 201, -66, -269, 805, -1407, 1740, -1268, -611, 4230, -9117, 13393, -13439, 4368, 18096, -53999, 94270, -116445, 84621, 41473, -284012, 611172, -896859, 898534, -289037, -1217319, 3622209, -6316136, 7792744, -5647143, -2814594 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..43.

Index entries for linear recurrences with constant coefficients, signature (-2, -1, 1).

FORMULA

G.f.: 1/((1+x)^2-x^3); a(n)=sum{k=0..n+4, (-1)^(n-k-1)*C(n+3, k)*sum{j=0..floor(k/3), C(k-2j, j)}}. - Paul Barry, May 10 2005

MATHEMATICA

CoefficientList[Series[1/(1+2x+x^2-x^3), {x, 0, 50}], x] (* or *) LinearRecurrence[ {-2, -1, 1}, {1, -2, 3}, 50] (* Harvey P. Dale, Aug 10 2016 *)

PROG

(PARI) Vec(1/(1+2*x+x^2-x^3)+O(x^99)) \\ Charles R Greathouse IV, Sep 26 2012

CROSSREFS

Sequence in context: A089283 A288531 A077941 * A085667 A220114 A035516

Adjacent sequences:  A077987 A077988 A077989 * A077991 A077992 A077993

KEYWORD

sign,easy

AUTHOR

N. J. A. Sloane, Nov 17 2002

STATUS

approved

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Last modified October 15 15:30 EDT 2018. Contains 316236 sequences. (Running on oeis4.)