OFFSET
0,1
COMMENTS
a(n) = T(n, 3), array T as in A049615.
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (0,1,1,0,-1).
FORMULA
G.f.: 2 -x*(-2-4*x-4*x^2-2*x^3+x^4)/( (1+x)*(1+x+x^2)*(x-1)^2 ). - R. J. Mathar, Oct 26 2015
MATHEMATICA
CoefficientList[Series[2 - x*(-2 - 4*x - 4*x^2 - 2*x^3 + x^4)/((1 + x)*(1 + x + x^2)*(x - 1)^2), {x, 0, 30}], x] (* G. C. Greubel, Dec 15 2017 *)
PROG
(PARI) x='x+O('x^30); Vec(2 -x*(-2-4*x-4*x^2-2*x^3+x^4)/( (1+x)*(1+x+x^2)*(x-1)^2 )) \\ G. C. Greubel, Dec 15 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
EXTENSIONS
Terms a(38) onward added by G. C. Greubel, Dec 15 2017
STATUS
approved