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 A052323 #15 Mar 29 2014 09:09:10
%S A052323 1,1,1,3,4,65,576,5887,92464,1680345,34041520,774906011,19537590744,
%T A052323 540890740117,16321259150392,533305854910935,18764822871806176,
%U A052323 707498057530634033,28460428902580264416,1216828054782241792435
%N A052323 Number of labeled trees with a forbidden limb of length 3.
%C A052323 A tree with a forbidden limb of length k is a tree where the path from any leaf inward hits a branching node or another leaf within k steps.
%H A052323 Vincenzo Librandi, <a href="/A052323/b052323.txt">Table of n, a(n) for n = 0..200</a>
%H A052323 <a href="/index/Tra#trees">Index entries for sequences related to trees</a>
%F A052323 E.g.f.: 1+x^4/2+x^5/2+x^6/2+B(x)-B(x)^2/2 where B(x) is e.g.f. of A052322.
%F A052323 a(n) ~ (1+LambertW(-3*exp(-3)))^(3/2) * exp(n/3*LambertW(-3*exp(-3))) * n^(n-2). - _Vaclav Kotesovec_, Mar 29 2014
%t A052323 CoefficientList[Series[1+x^4/2+x^5/2+x^6/2-LambertW[-x*E^(-x^3)]-(LambertW[-x*E^(-x^3)])^2/2, {x, 0, 20}], x] * Range[0, 20]! (* _Vaclav Kotesovec_, Mar 29 2014 *)
%Y A052323 Cf. A002955, A002988-A002992, A052318-A052329.
%K A052323 nonn
%O A052323 0,4
%A A052323 _Christian G. Bower_, Dec 15 1999