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A192867
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Number of set partitions of {1, ..., n} that avoid enhanced 7-crossings (or enhanced 7-nestings)
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0
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1, 1, 2, 5, 15, 52, 203, 877, 4140, 21147, 115975, 678570, 4213597, 27644436, 190899266, 1382956734, 10480097431, 82863928963, 682058946982, 5832425824171, 51718812364549
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OFFSET
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0,3
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LINKS
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EXAMPLE
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There are 27644437 partitions of 13 elements, but a(13)=27644436 because the partition {1,13}{2,12}{3,11}{4,10}{5,9}{6,8} {7} has an enhanced 7-nesting.
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CROSSREFS
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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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