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A318129
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Number of sets of nonempty subsets of {1,...,n} with intersection {}.
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9
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1, 1, 3, 91, 31827, 2147158387, 9223372011085950171, 170141183460469231602560095290109272523, 57896044618658097711785492504343953923912733397452774312538303978325772978595
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OFFSET
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0,3
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LINKS
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FORMULA
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a(n) = A318130(n) - 2^(2^(n - 1) - 1).
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EXAMPLE
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The a(2) = 3 sets of sets are {}, {{1},{2}}, {{1},{2},{1,2}}.
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MATHEMATICA
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Table[Length[Select[Subsets[Rest[Subsets[Range[n]]]], Or[#=={}, Intersection@@#=={}]&]], {n, 0, 4}]
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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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