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 A052525 #15 Apr 18 2017 07:03:25
%S A052525 0,0,0,1,1,2,3,6,10,20,36,71,136,270,531,1070,2147,4367,8895,18262,
%T A052525 37588,77795,161444,336383,702732,1472582,3093151,6513402,13744384,
%U A052525 29063588,61570853,130669978,277767990,591373581,1260855164
%N A052525 Number of unlabeled rooted trees with n leaves in which the degrees of the root and all internal nodes are >= 3.
%C A052525 Old name was "Non-planar unlabeled trees with neither unary nor binary nodes". I am leaving this alternative name here because it may help clarify the definitions of related sequences. - _N. J. A. Sloane_.
%H A052525 Vaclav Kotesovec, <a href="/A052525/b052525.txt">Table of n, a(n) for n = 0..1000</a>
%H A052525 INRIA Algorithms Project, <a href="http://ecs.inria.fr/services/structure?nbr=95">Encyclopedia of Combinatorial Structures 95</a>
%F A052525 a(n) ~ c * d^n / n^(3/2), where d = 2.2318799173898687960533559522113115638..., c = 0.3390616344584879699709248904124... . - _Vaclav Kotesovec_, May 04 2015
%e A052525 For instance, with 7 leaves, the 6 choices are:
%e A052525 . [ *,*,*,*,*,*,* ]
%e A052525 . [ *,*,*,*,[ *,*,* ] ]
%e A052525 . [ *,*,*,[ *,*,*,* ] ]
%e A052525 . [ *,*,[ *,*,*,*,* ] ]
%e A052525 . [ *,*,[ *,*,[ *,*,* ] ] ]
%e A052525 . [ *,[ *,*,* ],[ *,*,* ] ]
%p A052525 spec := [ S, {B=Union(S, Z), S=Set(B, 3 <= card)}, unlabeled ]: seq(combstruct[ count ](spec, size=n), n=0..50);
%Y A052525 Cf. A052524 and A052526.
%K A052525 easy,nonn
%O A052525 0,6
%A A052525 encyclopedia(AT)pommard.inria.fr, Jan 25 2000
%E A052525 More terms from _Paul Zimmermann_, Oct 31 2002