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Search: id:A120412
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| A120412 |
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Number of different graphs with n = number of vertices plus number of edges. |
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+0
1
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| 1, 1, 2, 2, 3, 5, 7, 10, 16, 25, 40, 66, 111
(list; graph; listen)
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OFFSET
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1,3
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COMMENT
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Given two integers p, q, one can count the number of different graphs having p vertices and q edges by the standard Polya counting technique. Our sequence is then obtained by summing up the terms with p+q=n.
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EXAMPLE
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a(3) = 2 because there is a graph with 3 vertices and no edges and a graph with 2 vertices and one edge.
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CROSSREFS
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Sequence in context: A058278 A097333 A001083 this_sequence A022864 A039894 A133225
Adjacent sequences: A120409 A120410 A120411 this_sequence A120413 A120414 A120415
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KEYWORD
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nonn
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AUTHOR
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Petr Vojtechovsky (petr(AT)math.du.edu), Jul 05 2006
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