A058642 Number of unlabeled graphs with n edges, no nodes of degree 1 or 2, no multiple edges and no cut nodes, under "series-equivalence".

0, 0, 0, 0, 0, 1, 0, 1, 3, 5, 9

Offset: 1

Author

N. J. A. Sloane, Dec 30 2000

Keywords

• nonn
• nice
• more

Comments

Under "series-equivalence" two graphs are equivalent if one can be obtained from the other by exchanging two subgraphs in series: replacing -A-B- by -B-A-.

Examples

			The first example, with 6 edges, is K_4. The second example has 8 edges and is the 1-skeleton of the square pyramid.
		

References

• B. D. H. Tellegen, Geometrical configurations and duality of electrical networks, Philips Technical Review, 5 (1940), 324-330.

Crossrefs

Cf. A058668.