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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". 2
0, 0, 0, 0, 0, 1, 0, 1, 3, 5, 9 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,9

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-.

REFERENCES

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

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 1-skeleton 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

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Last modified May 9 15:34 EDT 2021. Contains 343742 sequences. (Running on oeis4.)