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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

%I

%S 1,1,2,3,7,15,52,236,2018,33044,1181670,87720798,12886156666,

%T 3633055848955,1944000061673516,1967881435350411681,

%U 3768516013573481061951,13670271805989797561408684

%N 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.

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

%H Max Alekseyev, <a href="/A133736/b133736.txt">Table of n, a(n) for n = 1..60</a>

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

%Y A variant of A002854. See also A003049.

%K nonn

%O 1,3

%A _N. J. A. Sloane_, based on email from Max Alekseyev, Jan 28 2010

%E Edited and extended by _Max Alekseyev_, Jan 28 2010

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Last modified November 21 06:00 EST 2019. Contains 329350 sequences. (Running on oeis4.)