A112948 Number of unrooted regular planar maps of valency 3 with 2n vertices (considered up to orientation-preserving homeomorphisms).

2, 6, 26, 191, 1904, 22078, 282388, 3848001, 54953996, 814302292

Offset

1,1

Links

Table of n, a(n) for n=1..10.

Z. C. Gao, V. A. Liskovets and N. C. Wormald, Enumeration of unrooted odd-valent regular planar maps, Preprint, 2005.

Mark van Hoeij, Vijay Jung Kunwar, Classifying (near)-Belyi maps with Five Exceptional Points, arXiv preprint arXiv:1604.08158, 2016. Also in Indagationes Mathematicae (2019) Vol. 30, No. 1, 136-156.

Example

There exist 2 planar maps with two 3-valent vertices: a map with three parallel edges and a map with one loop in each vertex and a link. Therefore a(1)=2.

Crossrefs

Cf. A112944, A112945, A112949, A005470.

Sequence in context: A355211 A211604 A032014 * A007139 A306147 A331937

Adjacent sequences: A112945 A112946 A112947 * A112949 A112950 A112951

Keyword

nonn

Author

Valery A. Liskovets, Oct 10 2005

Status

approved