A340813 Number of oriented polygonal 2-trees with n oriented quadrilaterals.

1, 1, 1, 3, 11, 49, 252, 1406, 8405, 52348, 337029, 2225333, 15002763, 102896407, 716106077, 5046649182, 35956186581, 258649116963, 1876462272125, 13717081730294, 100957850485311, 747631534534529, 5567459642741752, 41671027665802639, 313351688709886964, 2366390596263188755

Offset: 0

Author

Andrew Howroyd, Feb 02 2021

Keywords

• nonn

Links

• Andrew Howroyd, Table of n, a(n) for n = 0..200
• G. Labelle, C. Lamathe and P. Leroux, Labeled and unlabeled enumeration of k-gonal 2-trees, arXiv:math/0312424 [math.CO], Dec 23 2003.

Crossrefs

Column k=4 of A340812.

Programs

PARI

C(25,4) \\ See A340812 for C(n,k).