Skeleton

The Graph obtained by collapsing a Polyhedron into the Plane. The number of topologically distinct skeletons $N(n)$ with $n$ Vertices is given in the following table.

$n$	$N(n)$
4	1
5	2
6	7

References

Gardner, M. Martin Gardner's New Mathematical Diversions from Scientific American. New York: Simon and Schuster, p. 233, 1966.