A319631 Number of non-isomorphic weight-n antichains of multisets whose dual is a chain of distinct multisets.

1, 1, 2, 3, 5, 5, 13, 11, 25, 31, 54

Offset: 0

Author

Gus Wiseman, Sep 25 2018

Keywords

• nonn
• more

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.

Examples

			Non-isomorphic representatives of the a(1) = 1 through a(5) = 5 antichains:
1: {{1}}
2: {{1,1}}
   {{1},{1}}
3: {{1,1,1}}
   {{1,2,2}}
   {{1},{1},{1}}
4: {{1,1,1,1}}
   {{1,2,2,2}}
   {{1,1},{1,1}}
   {{1,2},{2,2}}
   {{1},{1},{1},{1}}
5: {{1,1,1,1,1}}
   {{1,1,2,2,2}}
   {{1,2,2,2,2}}
   {{1,2},{2,2,2}}
   {{1},{1},{1},{1},{1}}
		

Crossrefs

Cf. A000219, A006126, A007716, A059201, A293606, A316980, A316983, A318099, A319558, A319616-A319646, A300913.