

A058642


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


2



0, 0, 0, 0, 0, 1, 0, 1, 3, 5, 9
(list;
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listen;
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internal format)



OFFSET

1,9


COMMENTS

Under "seriesequivalence" two graphs are equivalent if one can be obtained from the other by exchanging two subgraphs in series: replacing AB by BA.


REFERENCES

B. D. H. Tellegen, Geometrical configurations and duality of electrical networks, Philips Technical Review, 5 (1940), 324330.


LINKS

Table of n, a(n) for n=1..11.


EXAMPLE

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


CROSSREFS

Cf. A058668.
Sequence in context: A121371 A067094 A272235 * A258086 A141251 A186190
Adjacent sequences: A058639 A058640 A058641 * A058643 A058644 A058645


KEYWORD

nonn,nice,more


AUTHOR

N. J. A. Sloane, Dec 30 2000


STATUS

approved



