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 A273723 #12 Feb 24 2025 15:37:50 %S A273723 1,1,6,7484400,35417271278873496315860673177600000000 %N A273723 Number of ternary heaps on n levels (i.e., of (3^n-1)/2 elements). %C A273723 a(n) is also the number of labeled histories for a fully symmetric trifurcating labeled topology with 3^n leaves. - _Noah A Rosenberg_, Feb 24 2025 %H A273723 Alois P. Heinz, <a href="/A273723/b273723.txt">Table of n, a(n) for n = 0..6</a> %H A273723 E. H. Dickey, N. A. Rosenberg, <a href="https://doi.org/10.1098/rstb.2023.0307">Labelled histories with multifurcation and simultaneity</a>, Phil. Trans. R. Soc. B 380 (2025), 20230307. %H A273723 Wikipedia, <a href="https://en.wikipedia.org/wiki/D-ary_heap">D-ary heap</a> %F A273723 a(n) = A178008(A003462(n)). %Y A273723 Column k=3 of A273712. %Y A273723 Cf. A003462, A178008. %K A273723 nonn %O A273723 0,3 %A A273723 _Alois P. Heinz_, May 28 2016