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 A058380 #20 Dec 16 2024 13:28:03
%S A058380 0,0,1,1,13,66,796,8338,122326,1893748,34717076,695343144,15560613872,
%T A058380 379211091416,10070672083928,288420300817184,8877044175277216,
%U A058380 291944826030636000,10221726849956763136,379528960298122277536,14896869800297864928736
%N A058380 Essentially series series-parallel networks with n labeled edges, multiple edges not allowed.
%H A058380 Steven R. Finch, <a href="http://www.people.fas.harvard.edu/~sfinch/">Series-parallel networks</a>
%H A058380 Steven R. Finch, <a href="/A000084/a000084_2.pdf">Series-parallel networks</a>, July 7, 2003. [Cached copy, with permission of the author]
%H A058380 John W. Moon, <a href="http://dx.doi.org/10.1016/S0304-0208(08)73057-3">Some enumerative results on series-parallel networks</a>, Annals Discrete Math., 33 (1987), 199-226 (the sequence R_n).
%H A058380 <a href="/index/Mo#Moon87">Index entries for sequences mentioned in Moon (1987)</a>
%F A058380 E.g.f. satisfies A(x) = A058379(x) - log(1+x).
%F A058380 E.g.f.: -1/2 - log(1+x)/2 - LambertW(-exp(-1/2)*sqrt(1+x)/2). - _Vaclav Kotesovec_, Mar 11 2014
%F A058380 a(n) ~ n^(n-1) / (2*sqrt(2)*(4-exp(1))^(n-1/2)). - _Vaclav Kotesovec_, Mar 11 2014
%t A058380 CoefficientList[Series[-1/2 - Log[1+x]/2 - LambertW[-E^(-1/2)*Sqrt[1+x]/2], {x, 0, 15}], x]* Range[0, 15]! (* _Vaclav Kotesovec_, Mar 11 2014 *)
%Y A058380 Cf. A058379, A058381.
%K A058380 nonn,nice,easy
%O A058380 0,5
%A A058380 _N. J. A. Sloane_, Dec 19 2000