A321409 Number of non-isomorphic self-dual multiset partitions of weight n whose part sizes are relatively prime.

1, 1, 1, 3, 6, 16, 27, 71, 135, 309, 621

Offset: 0

Author

Gus Wiseman, Nov 16 2018

Keywords

• nonn
• more

Comments

Also the number of nonnegative integer symmetric matrices up to row and column permutations with sum of elements equal to n and no zero rows or columns, with relatively prime row sums (or column sums).

The dual of a multiset partition has, for each vertex, one part consisting of the indices (or positions) of the parts 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) = 16 multiset partitions:
  {{1}}  {{1}{2}}  {{1}{22}}    {{1}{222}}      {{11}{122}}
                   {{2}{12}}    {{2}{122}}      {{11}{222}}
                   {{1}{2}{3}}  {{1}{1}{23}}    {{12}{122}}
                                {{1}{2}{33}}    {{1}{2222}}
                                {{1}{3}{23}}    {{2}{1222}}
                                {{1}{2}{3}{4}}  {{1}{22}{33}}
                                                {{1}{23}{23}}
                                                {{1}{2}{333}}
                                                {{1}{3}{233}}
                                                {{2}{12}{33}}
                                                {{2}{13}{23}}
                                                {{3}{3}{123}}
                                                {{1}{2}{2}{34}}
                                                {{1}{2}{3}{44}}
                                                {{1}{2}{4}{34}}
                                                {{1}{2}{3}{4}{5}}
		

Crossrefs

Cf. A000219, A007716, A120733, A138178, A316983, A319616.

Cf. A320796, A320797, A320800, A320805, A320806, A320809, A320811, A320813, A321283, A321410, A321411, A321413.