A136797 Number of labeled marked trees with n nodes.

2, 8, 96, 2048, 64000, 2654208, 137682944, 8589934592, 626913312768, 52428800000000, 4944974716076032, 519400496868360192, 60134924074807721984, 7609328110443312447488, 1044855521280000000000000, 154742504910672534362390528, 24588026787102364507838611456

Offset: 1

Author

Christian G. Bower, Jan 21 2008

Keywords

• nonn

Comments

A marked tree is a tree where each node and edge is marked as + or -.

References

• F. Bergeron, G. Labelle and P. Leroux, Combinatorial Species and Tree-Like Structures, Cambridge, 1998, p. 293 (4.1.60).

Links

• Andrew Howroyd, Table of n, a(n) for n = 1..200
• Index entries for sequences related to trees

Crossrefs

Cf. A136796.

Programs

Mathematica

Table[2^(2n-1) n^(n-2),{n,20}] (* Harvey P. Dale, Nov 17 2024 *)

PARI

a(n) = {2^(2*n-1) * n^(n-2)} \\ Andrew Howroyd, Feb 02 2020

Formula

a(n) = A136796(n)/n.

a(n) = 2^(2*n-1) * n^(n-2). - Andrew Howroyd, Feb 02 2020

Extensions

Terms a(15) and beyond from Andrew Howroyd, Feb 02 2020