A097632 2^n * Lucas(n).

2, 12, 64, 672, 8448, 138240, 2672640, 60641280, 1568931840, 45705461760, 1478924697600, 52646746521600, 2044394156851200, 86005817907609600, 3896481847600742400, 189139342470414336000, 9793081532749971456000

Offset

1,1

Comments

Number of possible well-colored cycles on n nodes. Well-colored means, each green vertex has at least a red child, each red vertex has no red child.

Links

Table of n, a(n) for n=1..17.

C. Banderier, J.-M. Le Bars and V. Ravelomanana, Generating functions for kernels of digraphs

Formula

E.g.f.: -log(1-2x-4x^2). Contrary to b(n) = 2^n*Fib(n), there seems to be no rational o.g.f. for the sequence.

Crossrefs

Equals A000079(n) * A000204(n).

Sequence in context: A226226 A126737 A345697 * A076804 A190153 A334772

Adjacent sequences: A097629 A097630 A097631 * A097633 A097634 A097635

Keyword

nonn

Author

Ralf Stephan, Aug 17 2004

Status

approved