
COMMENTS

The dual of a multiset partition has, for each vertex, one block consisting of the indices (or positions) of the blocks containing that vertex, counted with multiplicity. For example, the dual of {{1,2},{2,2}} is {{1},{1,2,2}}.
The weight of a multiset partition is the sum of sizes of its parts. Weight is generally not the same as number of vertices.


EXAMPLE

Nonisomorphic representatives of the a(1) = 1 through a(10) = 3 antichains:
{{1}}
{{1,2},{1,3},{2,3}}
{{1,2},{1,3},{2,4},{3,4}}
{{1,2},{1,3},{1,4},{2,3,4}}
{{1,3},{2,4},{1,2,5},{3,4,5}}
{{1,2},{1,3},{2,4},{3,5},{4,5}}
{{1,3},{1,4},{2,3},{2,4},{3,4}}
