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Search: id:A118077
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| A118077 |
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Number of edges in the representation of all linear extensions of the inclusion ordering on P({1,...,n}) as distributive lattice contained in P(P({1,...,n})). |
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+0
2
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OFFSET
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0,2
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COMMENT
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The numbers of vertices are the Dedekind numbers (A000372) and A046873 is the total number of linear extensions.
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EXAMPLE
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a(1) = 6 as the lattice is { {}, { {} }, { {}, {1} }, { {}, {2} }, { {}, {1}, {2}}, { {}, {1}, {2}, {1, 2} } }.
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PROGRAM
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Python, using an inference method for computing the set of linear extensions of arbitrary posets.
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CROSSREFS
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Cf. A046873, A000372.
Sequence in context: A001199 A034997 A067735 this_sequence A013976 A083666 A083126
Adjacent sequences: A118074 A118075 A118076 this_sequence A118078 A118079 A118080
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KEYWORD
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hard,nonn
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AUTHOR
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Oliver W. Wienand (wienand(AT)mathematik.uni-kl.de), Apr 11 2006
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