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 A330627 #8 Jan 02 2021 21:21:34 %S A330627 0,1,1,1,2,2,4,5,9,14,24,39,69,116,205,357,632,1118,2001,3576,6445, %T A330627 11627,21080,38293,69819,127539,233644,428825,788832,1453589,2683602, %U A330627 4962167,9190155,17044522,31655676,58866237,109600849,204293047,381212823,712073862 %N A330627 Number of non-isomorphic phylogenetic trees with n nodes. %C A330627 A phylogenetic tree is a series-reduced rooted tree whose leaves are (usually disjoint) sets. Each branching as well as each element of each leaf contributes to the number of nodes. %H A330627 Andrew Howroyd, <a href="/A330627/b330627.txt">Table of n, a(n) for n = 1..500</a> %F A330627 G.f.: A(x) satisfies A(x) = x*(1/(1-x) - A(x) - 2 + exp(Sum_{k>0} A(x^k)/k)). - _Andrew Howroyd_, Jan 02 2021 %e A330627 Non-isomorphic representatives of the a(2) = 1 through a(9) = 9 trees (commas and outer brackets elided): %e A330627 1 12 123 1234 12345 123456 1234567 12345678 %e A330627 (1)(2) (1)(23) (1)(234) (1)(2345) (1)(23456) %e A330627 (12)(34) (12)(345) (12)(3456) %e A330627 (1)(2)(3) (1)(2)(34) (123)(456) %e A330627 (1)((2)(3)) (1)(2)(345) %e A330627 (1)(23)(45) %e A330627 (1)((2)(34)) %e A330627 (1)(2)(3)(4) %e A330627 (12)((3)(4)) %o A330627 (PARI) EulerT(v)={Vec(exp(x*Ser(dirmul(v,vector(#v,n,1/n))))-1, -#v)} %o A330627 seq(n)={my(v=[0]); for(n=1, n-1, v=concat(v, EulerT(v)[n] - v[n] + 1)); v} \\ _Andrew Howroyd_, Jan 02 2021 %Y A330627 Phylogenetic trees by number of labels are A005804, with unlabeled version A141268. %Y A330627 Balanced phylogenetic trees are A320154. %Y A330627 Cf. A000311, A000669, A001678, A004114, A005121, A007716, A048816, A060356, A330465, A330467, A330469. %K A330627 nonn %O A330627 1,5 %A A330627 _Gus Wiseman_, Dec 28 2019 %E A330627 Terms a(11) and beyond from _Andrew Howroyd_, Jan 02 2021