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A010357
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Number of unlabeled nonseparable (or 2-connected) loopless multigraphs with n edges.
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5
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1, 1, 2, 3, 6, 14, 32, 90, 279, 942, 3468, 13777, 57747, 254671, 1170565, 5580706, 27487418, 139477796, 727458338, 3893078684, 21346838204, 119787629215, 687200870250
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OFFSET
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1,3
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COMMENTS
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Original name: Multi-edge stars with n edges.
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LINKS
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Brendan McKay and Adolfo Piperno, nauty and Traces, programs for computing automorphism groups of graphs and digraphs.
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EXAMPLE
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The a(1) = 1 graph is a single edge (K_2 = P_2).
The a(2) = 1 graph is a double edge.
The a(3) = 2 graphs are a triple edge and the triangle (K_3).
The a(4) = 3 graphs are a quadruple edge, a triangle with one double edge and the square (C_4).
(End)
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CROSSREFS
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A002218 counts unlabeled 2-connected graphs.
A013922 counts labeled 2-connected graphs.
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KEYWORD
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nonn,more
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AUTHOR
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EXTENSIONS
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a(11)-a(20) added using geng/multig from nauty by Andrew Howroyd, Dec 05 2020
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STATUS
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approved
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