This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A133736 #13 Jul 04 2024 23:46:48
%S A133736 1,1,2,3,7,15,52,236,2018,33044,1181670,87720798,12886156666,
%T A133736 3633055848955,1944000061673516,1967881435350411681,
%U A133736 3768516013573481061951,13670271805989797561408684
%N 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.
%C A133736 Any such graph consists of a single connected Euler graph (see A003049) plus a number of isolated vertices.
%H A133736 Chai Wah Wu, <a href="/A133736/b133736.txt">Table of n, a(n) for n = 1..88</a> (terms 1..60 from Max Alekseyev)
%F A133736 a(n) = Sum_{k=1..n} A003049(k).
%Y A133736 A variant of A002854. See also A003049.
%K A133736 nonn
%O A133736 1,3
%A A133736 _N. J. A. Sloane_, based on email from Max Alekseyev, Jan 28 2010
%E A133736 Edited and extended by _Max Alekseyev_, Jan 28 2010