OFFSET
0,3
LINKS
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 1055
Index entries for linear recurrences with constant coefficients, signature (2,2,0,-1).
FORMULA
G.f.: (1-x)/(1-2*x-2*x^2+x^4).
Recurrence: {a(1)=1, a(0)=1, a(2)=4, a(3)=10, a(n)-2*a(n+2)-2*a(n+3)+a(n+4)=0}.
Sum(-1/182*(-35*_alpha+2*_alpha^3+22*_alpha^2-25)*_alpha^(-1-n), _alpha=RootOf(1-2*_Z-2*_Z^2+_Z^4)).
MAPLE
spec := [S, {S=Sequence(Prod(Union(Prod(Z, Z), Z), Union(Sequence(Z), Z)))}, unlabeled ]: seq(combstruct[count ](spec, size=n), n=0..20);
MATHEMATICA
CoefficientList[Series[(1 - x)/(1 - 2*x - 2*x^2 + x^4), {x, 0, 30}], x] (* Wesley Ivan Hurt, Nov 13 2014 *)
LinearRecurrence[{2, 2, 0, -1}, {1, 1, 4, 10}, 30] (* Harvey P. Dale, Oct 03 2016 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
encyclopedia(AT)pommard.inria.fr, Jan 25 2000
EXTENSIONS
More terms from James A. Sellers, Jun 06 2000
STATUS
approved