1,1

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.

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

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.

Equals A000079(n) * A000204(n).

Sequence in context: A052896 A025599 A126737 this_sequence A076804 A039633 A020062

Adjacent sequences: A097629 A097630 A097631 this_sequence A097633 A097634 A097635

nonn

Ralf Stephan, Aug 17 2004