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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. 3
1, 1, 2, 3, 7, 15, 52, 236, 2018, 33044, 1181670, 87720798, 12886156666, 3633055848955, 1944000061673516, 1967881435350411681, 3768516013573481061951, 13670271805989797561408684 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

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

LINKS

Max Alekseyev, Table of n, a(n) for n = 1..60

FORMULA

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

CROSSREFS

A variant of A002854. See also A003049.

Sequence in context: A034731 A216435 A110888 * A058698 A058699 A250193

Adjacent sequences:  A133733 A133734 A133735 * A133737 A133738 A133739

KEYWORD

nonn

AUTHOR

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

EXTENSIONS

Edited and extended by Max Alekseyev, Jan 28 2010

STATUS

approved

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Last modified November 20 13:59 EST 2017. Contains 294972 sequences.