login
Number of non-isomorphic intersecting strict T_0 multiset partitions of weight n.
4

%I #5 Sep 28 2018 15:24:11

%S 1,1,1,4,7,17,42,98,248,631,1657

%N Number of non-isomorphic intersecting strict T_0 multiset partitions of weight n.

%C A multiset partition is intersecting iff no two parts are disjoint. The weight of a multiset partition is the sum of sizes of its parts. 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 T_0 condition means the dual is strict.

%e Non-isomorphic representatives of the a(1) = 1 through a(4) = 7 multiset partitions:

%e 1: {{1}}

%e 2: {{1,1}}

%e 3: {{1,1,1}}

%e {{1,2,2}}

%e {{1},{1,1}}

%e {{2},{1,2}}

%e 4: {{1,1,1,1}}

%e {{1,2,2,2}}

%e {{1},{1,1,1}}

%e {{1},{1,2,2}}

%e {{2},{1,2,2}}

%e {{1,2},{2,2}}

%e {{1,3},{2,3}}

%Y Cf. A007716, A049311, A059201, A281116, A283877, A305843, A305854, A306006, A316980.

%Y Cf. A319755, A319759, A319760, A319765, A319779, A319787, A319789.

%K nonn,more

%O 0,4

%A _Gus Wiseman_, Sep 27 2018