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A318399
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Number of triples of set partitions of {1,...,n} with meet {{1},...,{n}} and join {{1,...,n}}.
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3
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1, 6, 84, 2226, 93246, 5616492, 459173406, 48933260388, 6595445513412, 1098326915060730, 221772386369110242, 53460963703982862534, 15185890964240671486740, 5026315912246843181692776, 1919721040169845172603949966, 838872819016448052585038291124
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OFFSET
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1,2
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LINKS
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FORMULA
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EXAMPLE
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The a(2) = 6 triples:
{{1},{2}} {{1},{2}} {{1,2}}
{{1},{2}} {{1,2}} {{1},{2}}
{{1},{2}} {{1,2}} {{1,2}}
{{1,2}} {{1},{2}} {{1},{2}}
{{1,2}} {{1},{2}} {{1,2}}
{{1,2}} {{1,2}} {{1},{2}}
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MATHEMATICA
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nn=20;
Table[n!*SeriesCoefficient[Log[1+Sum[x^k/k!*Sum[StirlingS1[k, i]*BellB[i]^3, {i, 0, k}], {k, nn}]], {x, 0, n}], {n, nn}]
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CROSSREFS
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Cf. A000110, A000258, A001247, A008277, A048994, A059849, A060639, A181939, A318389, A318390, A318391, A318392, A318393, A318398.
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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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