OFFSET
0,4
COMMENTS
Equally, expansion of (1-x)^(-1)/(1+x+2*x^2).
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (0, -1, 2).
FORMULA
a(0)=1, a(1)=0, a(2)=-1, a(n) = -a(n-2)+2*a(n-3). - Harvey P. Dale, Dec 10 2012
a(n) = (-1)^n * A077963(n). - G. C. Greubel, Jun 23 2019
MATHEMATICA
CoefficientList[Series[1/(1+x^2-2*x^3), {x, 0, 50}], x] (* or *) LinearRecurrence[{0, -1, 2}, {1, 0, -1}, 50] (* Harvey P. Dale, Dec 10 2012 *)
PROG
(PARI) my(x='x+O('x^50)); Vec(1/(1+x^2-2*x^3)) \\ G. C. Greubel, Jun 23 2019
(Magma) R<x>:=PowerSeriesRing(Integers(), 50); Coefficients(R!( 1/(1+x^2-2*x^3) )); // G. C. Greubel, Jun 23 2019
(Sage) (1/(1+x^2-2*x^3)).series(x, 50).coefficients(x, sparse=False) # G. C. Greubel, Jun 23 2019
(GAP) a:=[1, 0, -1];; for n in [4..50] do a[n]:=-a[n-2]+2*a[n-3]; od; a; # G. C. Greubel, Jun 23 2019
CROSSREFS
KEYWORD
sign,easy
AUTHOR
N. J. A. Sloane, Nov 17 2002
STATUS
approved