A133736 Number of graphs on n unlabeled nodes that have an Eulerian cycle, i.e., a cycle that goes through every edge in the graph exactly once.

1, 1, 2, 3, 7, 15, 52, 236, 2018, 33044, 1181670, 87720798, 12886156666, 3633055848955, 1944000061673516, 1967881435350411681, 3768516013573481061951, 13670271805989797561408684

Offset: 1

Author

N. J. A. Sloane, based on email from Max Alekseyev, Jan 28 2010

Keywords

• nonn

Comments

Any such graph consists of a single connected Euler graph (see A003049) plus a number of isolated vertices.

Links

• Chai Wah Wu, Table of n, a(n) for n = 1..88 (terms 1..60 from Max Alekseyev)

Crossrefs

A variant of A002854. See also A003049.

Formula

a(n) = Sum_{k=1..n} A003049(k).

Extensions

Edited and extended by Max Alekseyev, Jan 28 2010