A273723 Number of ternary heaps on n levels (i.e., of (3^n-1)/2 elements).

1, 1, 6, 7484400, 35417271278873496315860673177600000000

Offset

0,3

Comments

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

Links

Alois P. Heinz, Table of n, a(n) for n = 0..6

E. H. Dickey, N. A. Rosenberg, Labelled histories with multifurcation and simultaneity, Phil. Trans. R. Soc. B 380 (2025), 20230307.

Wikipedia, D-ary heap

Formula

a(n) = A178008(A003462(n)).

Crossrefs

Column k=3 of A273712.

Cf. A003462, A178008.

Sequence in context: A172876 A269516 A116272 * A182792 A067484 A337083

Adjacent sequences: A273720 A273721 A273722 * A273724 A273725 A273726

Keyword

nonn,changed

Author

Alois P. Heinz, May 28 2016

Status

approved