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 (2,0,-2).
FORMULA
a(n) = (-1)^n * A077988(n). - R. J. Mathar, Feb 04 2014
MATHEMATICA
LinearRecurrence[{2, 0, -2}, {1, 2, 4}, 50] (* or *) CoefficientList[Series[ 1/(1-2*x+2*x^3), {x, 0, 50}], x] (* G. C. Greubel, Jun 26 2019 *)
PROG
(PARI) my(x='x+O('x^50)); Vec(1/(1-2*x+2*x^3)) \\ G. C. Greubel, Jun 26 2019
(Magma) R<x>:=PowerSeriesRing(Integers(), 50); Coefficients(R!( 1/(1-2*x+2*x^3) )); // G. C. Greubel, Jun 26 2019
(Sage) (1/(1-2*x+2*x^3)).series(x, 50).coefficients(x, sparse=False) # G. C. Greubel, Jun 26 2019
(GAP) a:=[1, 2, 4];; for n in [4..50] do a[n]:=2*(a[n-1]-a[n-3]); od; a; # G. C. Greubel, Jun 26 2019
CROSSREFS
KEYWORD
sign,easy
AUTHOR
N. J. A. Sloane, Nov 17 2002
STATUS
approved