A273725 Number of quaternary heaps on n levels (i.e., of (4^n-1)/3 elements).

1, 1, 24, 3892643213082624

Offset

0,3

Comments

a(n) is also the number of labeled histories for a fully symmetric quadfurcating labeled topology with 4^n leaves. - Noah A Rosenberg, Feb 24 2025

Links

Alois P. Heinz, Table of n, a(n) for n = 0..5

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) = A178009(A002450(n)).

Crossrefs

Column k=4 of A273712.

Cf. A002450, A178009.

Sequence in context: A297424 A013910 A007458 * A072244 A067669 A068741

Adjacent sequences: A273722 A273723 A273724 * A273726 A273727 A273728

Keyword

nonn,changed

Author

Alois P. Heinz, May 28 2016

Status

approved