%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
