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A278691
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Number of graded lattices on n nodes.
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1
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1, 1, 1, 2, 4, 9, 22, 60, 176, 565, 1980, 7528, 30843, 135248, 630004, 3097780, 15991395, 86267557, 484446620, 2822677523, 17017165987
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OFFSET
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1,4
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COMMENTS
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A finite lattice is graded if, for any element, all paths from the bottom to that element have the same length.
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LINKS
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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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