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A319792
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Number of non-isomorphic connected set systems of weight n with empty intersection.
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1
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1, 0, 0, 0, 1, 2, 9, 22, 69, 190, 567, 1640, 5025, 15404, 49048, 159074, 531165, 1813627, 6352739, 22759620, 83443086, 312612543, 1196356133, 4672620842, 18615188819, 75593464871, 312729620542, 1317267618429, 5646454341658, 24618309943464, 109123789229297
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OFFSET
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0,6
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COMMENTS
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The weight of a set system is the sum of sizes of its parts. Weight is generally not the same as number of vertices.
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LINKS
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FORMULA
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EXAMPLE
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Non-isomorphic representatives of the a(4) = 1 through a(6) = 9 connected set systems:
4: {{1},{2},{1,2}}
5: {{2},{3},{1,2,3}}
{{2},{1,3},{2,3}}
6: {{1},{1,4},{2,3,4}}
{{1},{2,3},{1,2,3}}
{{3},{4},{1,2,3,4}}
{{3},{1,4},{2,3,4}}
{{1,2},{1,3},{2,3}}
{{1,3},{2,4},{3,4}}
{{1},{2},{3},{1,2,3}}
{{1},{2},{1,3},{2,3}}
{{2},{3},{1,3},{2,3}}
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CROSSREFS
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Cf. A007716, A007718, A049311, A056156, A281116, A283877, A300913, A305854, A316980, A317752, A317755, A317757.
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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