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A306008
Number of non-isomorphic intersecting set-systems of weight n with no singletons.
6
1, 0, 1, 1, 2, 3, 7, 10, 21, 39, 78
OFFSET
0,5
COMMENTS
An intersecting set-system is a finite set of finite nonempty sets (edges), any two of which have a nonempty intersection. The weight of a set-system is the sum of cardinalities of its elements. Weight is generally not the same as number of vertices.
EXAMPLE
Non-isomorphic representatives of the a(6) = 7 set-systems:
{{1,2,3,4,5,6}}
{{1,5},{2,3,4,5}}
{{3,4},{1,2,3,4}}
{{1,2,5},{3,4,5}}
{{1,3,4},{2,3,4}}
{{1,2},{1,3},{2,3}}
{{1,4},{2,4},{3,4}}
KEYWORD
nonn,more
AUTHOR
Gus Wiseman, Jun 16 2018
STATUS
approved