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 (-2,2,2).
FORMULA
a(n) = (-1)^n * A077937(n). - Ivan Neretin, Jun 19 2015
MATHEMATICA
LinearRecurrence[{-2, 2, 2}, {1, -2, 6}, 30] (* or *) CoefficientList[ Series[1/(1+2*x-2*x^2-2*x^3), {x, 0, 30}], x] (* G. C. Greubel, Jun 25 2019 *)
PROG
(PARI) Vec(1/(1+2*x-2*x^2-2*x^3) + O(x^30)) \\ Michel Marcus, Jun 19 2015
(Magma) R<x>:=PowerSeriesRing(Integers(), 30); Coefficients(R!( 1/(1+2*x-2*x^2-2*x^3) )); // G. C. Greubel, Jun 25 2019
(Sage) (1/(1+2*x-2*x^2-2*x^3)).series(x, 30).coefficients(x, sparse=False) # G. C. Greubel, Jun 25 2019
(GAP) a:=[1, -2, 6];; for n in [4..30] do a[n]:=-2*a[n-1]+2*a[n-2]+ 2*a[n-3]; od; a; # G. C. Greubel, Jun 25 2019
CROSSREFS
KEYWORD
sign,easy
AUTHOR
N. J. A. Sloane, Nov 17 2002
STATUS
approved