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A077973 Expansion of 1/(1+x-2*x^3). 9
1, -1, 1, 1, -3, 5, -3, -3, 13, -19, 13, 13, -51, 77, -51, -51, 205, -307, 205, 205, -819, 1229, -819, -819, 3277, -4915, 3277, 3277, -13107, 19661, -13107, -13107, 52429, -78643, 52429, 52429, -209715, 314573, -209715, -209715, 838861, -1258291, 838861, 838861, -3355443, 5033165, -3355443 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,5

LINKS

Table of n, a(n) for n=0..46.

Index entries for linear recurrences with constant coefficients, signature (-1,0,2).

FORMULA

a(n) = -a(n-1) +2*a(n-3). - Paul Curtz, Apr 23 2008

a(n) = (-1)^n * A077950(n) = (1/5) * (2*A134142(n) + 1). - Ralf Stephan, Aug 18 2013

G.f.: G(0)/(2*(1-x^2)), where G(k)= 1 + 1/(1 - x*(k+1)/(x*(k+2) - 1/G(k+1))); (continued fraction). - Sergei N. Gladkovskii, May 25 2013

MATHEMATICA

CoefficientList[Series[1/(1+x-2x^3), {x, 0, 50}], x] (* or *) LinearRecurrence[ {-1, 0, 2}, {1, -1, 1}, 50] (* Harvey P. Dale, Jun 09 2017 *)

PROG

(PARI) Vec(1/(1+x-2*x^3)+O(x^99)) \\ Charles R Greathouse IV, Sep 23 2012

CROSSREFS

Sequence in context: A133773 A077934 A077950 * A210606 A254327 A175999

Adjacent sequences:  A077970 A077971 A077972 * A077974 A077975 A077976

KEYWORD

sign,easy

AUTHOR

N. J. A. Sloane, Nov 17 2002, Jun 17 2007

STATUS

approved

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Last modified November 17 00:14 EST 2018. Contains 317275 sequences. (Running on oeis4.)