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Search: id:A058642
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| A058642 |
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Number of unlabeled graphs with n edges, no nodes of degree 1 or 2, no multiple edges and no cut nodes, under "series-equivalence". |
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+0
3
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| 0, 0, 0, 0, 0, 1, 0, 1, 3, 5, 9
(list; graph; listen)
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OFFSET
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1,9
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COMMENT
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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-.
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REFERENCES
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B. D. H. Tellegen, Geometrical configurations and duality of electrical networks, Philips Technical Review, 5 (1940), 324-330.
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EXAMPLE
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The first example, with 6 edges, is K_4. The second example has 8 edges and is the 1-skeleton of the square pyramid.
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CROSSREFS
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Cf. A058668.
Adjacent sequences: A058639 A058640 A058641 this_sequence A058643 A058644 A058645
Sequence in context: A109342 A121371 A067094 this_sequence A141251 A019739 A101298
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KEYWORD
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nonn,nice,more
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AUTHOR
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njas, Dec 30 2000
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