|
|
A112948
|
|
Number of unrooted 3-regular planar maps with 2n vertices, up to orientation-preserving isomorphisms.
|
|
2
|
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
A 3-regular map is a regular map with valency 3.
|
|
LINKS
|
|
|
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 connecting the vertices. Therefore a(1)=2.
|
|
CROSSREFS
|
3-regular maps on the torus: A292408.
|
|
KEYWORD
|
nonn,changed
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|