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A022017
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Number of connected partially ordered sets with n "lines": pairs (a,b) where a < b and there is no c with a < c < b. The lines form the minimal basis for the partial ordering.
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4
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OFFSET
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1,2
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COMMENTS
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The points are unlabeled.
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REFERENCES
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See A000112 for references and links about partially ordered sets.
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LINKS
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EXAMPLE
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See Sloane's link.
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CROSSREFS
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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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STATUS
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approved
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