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%I #11 Aug 14 2019 01:48:40
%S 1,0,1,6,76,12916
%N Number of unlabeled spanning intersecting set-systems on n vertices with no singletons.
%C An intersecting set-system S is a finite set of finite nonempty sets (edges), any two of which have a nonempty intersection. S is spanning if every vertex is contained in some edge. A singleton is an edge containing only one vertex.
%F a(n) = A306001(n) - A306001(n-1) for n > 0. - _Andrew Howroyd_, Aug 12 2019
%e Non-isomorphic representative of the a(3) = 6 set-systems:
%e {{1,2,3}}
%e {{1,3},{2,3}}
%e {{2,3},{1,2,3}}
%e {{1,2},{1,3},{2,3}}
%e {{1,3},{2,3},{1,2,3}}
%e {{1,2},{1,3},{2,3},{1,2,3}}
%Y Cf. A001206, A051185, A048143, A261006, A058891, A261005, A304998, A305854-A305857, A305935, A306000, A306001, A306008.
%K nonn,more
%O 0,4
%A _Gus Wiseman_, Jun 16 2018
%E a(5) from _Andrew Howroyd_, Aug 12 2019
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