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URL: https://oeis.org/A273723

⇱ A273723 - OEIS

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A273723
Number of ternary heaps on n levels (i.e., of (3^n-1)/2 elements).
3
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
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.
Sequence in context: A172876 A269516 A116272 * A182792 A067484 A337083
KEYWORD
nonn
AUTHOR
Alois P. Heinz, May 28 2016
STATUS
approved