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A327199
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Number of labeled simple graphs with n vertices whose edge-set is not connected.
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5
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1, 1, 1, 1, 4, 56, 1031, 27189, 1165424, 89723096, 13371146135, 3989665389689, 2388718032951812, 2852540291841718752, 6768426738881535155247, 31870401029679493862010949, 297787425565749788134314214272
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OFFSET
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0,5
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COMMENTS
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Also graphs with non-spanning edge-connectivity 0.
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LINKS
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FORMULA
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EXAMPLE
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The a(4) = 4 edge-sets: {}, {12,34}, {13,24}, {14,23}.
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MATHEMATICA
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csm[s_]:=With[{c=Select[Subsets[Range[Length[s]], {2}], Length[Intersection@@s[[#]]]>0&]}, If[c=={}, s, csm[Sort[Append[Delete[s, List/@c[[1]]], Union@@s[[c[[1]]]]]]]]];
Table[Length[Select[Subsets[Subsets[Range[n], {2}]], Length[csm[#]]!=1&]], {n, 0, 5}]
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CROSSREFS
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Cf. A001187, A006129, A322395, A326787, A327075, A327076, A327079, A327129, A327200, A327201, A327231, A327236.
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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