OFFSET

0,4

COMMENTS

The weight of a multiset partition is the sum of sizes of its parts. Weight is generally not the same as number of vertices. 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

Non-isomorphic representatives of the a(1) = 1 through a(6) = 7 antichains:

1: {{1}}

2: {{1,1}}

3: {{1,1,1}}

{{1,2,2}}

4: {{1,1,1,1}}

{{1,2,2,2}}

{{1,2},{2,2}}

5: {{1,1,1,1,1}}

{{1,1,2,2,2}}

{{1,2,2,2,2}}

{{1,2},{2,2,2}}

6: {{1,1,1,1,1,1}}

{{1,1,2,2,2,2}}

{{1,2,2,2,2,2}}

{{1,2,2,3,3,3}}

{{1,2},{2,2,2,2}}

{{1,2,2},{2,2,2}}

{{1,2,3},{2,3,3}}

CROSSREFS

KEYWORD

nonn,more

AUTHOR

Gus Wiseman, Sep 25 2018

STATUS

approved