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A318129
Number of sets of nonempty subsets of {1,...,n} with intersection {}.
9
1, 1, 3, 91, 31827, 2147158387, 9223372011085950171, 170141183460469231602560095290109272523, 57896044618658097711785492504343953923912733397452774312538303978325772978595
OFFSET
0,3
FORMULA
Binomial transform of A318128.
a(n) = A318130(n) - 2^(2^(n - 1) - 1).
EXAMPLE
The a(2) = 3 sets of sets are {}, {{1},{2}}, {{1},{2},{1,2}}.
MATHEMATICA
Table[Length[Select[Subsets[Rest[Subsets[Range[n]]]], Or[#=={}, Intersection@@#=={}]&]], {n, 0, 4}]
KEYWORD
nonn
AUTHOR
Gus Wiseman, Aug 18 2018
STATUS
approved