This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A321402 #4 Nov 13 2018 12:54:25
%S A321402 1,0,1,1,2,4,8,14,27,53,105
%N A321402 Number of non-isomorphic strict self-dual multiset partitions of weight n with no singletons.
%C A321402 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, in which the rows are all different and none sums to 1.
%C A321402 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}}.
%C A321402 The weight of a multiset partition is the sum of sizes of its parts. Weight is generally not the same as number of vertices.
%e A321402 Non-isomorphic representatives of the a(2) = 1 through a(7) = 14 multiset partitions:
%e A321402 {{11}} {{111}} {{1111}} {{11111}} {{111111}} {{1111111}}
%e A321402 {{11}{22}} {{11}{122}} {{111}{222}} {{111}{1222}}
%e A321402 {{11}{222}} {{112}{122}} {{111}{2222}}
%e A321402 {{12}{122}} {{11}{2222}} {{112}{1222}}
%e A321402 {{12}{1222}} {{11}{22222}}
%e A321402 {{22}{1122}} {{12}{12222}}
%e A321402 {{11}{22}{33}} {{122}{1122}}
%e A321402 {{12}{13}{23}} {{22}{11222}}
%e A321402 {{11}{12}{233}}
%e A321402 {{11}{22}{233}}
%e A321402 {{11}{22}{333}}
%e A321402 {{11}{23}{233}}
%e A321402 {{12}{13}{233}}
%e A321402 {{13}{23}{123}}
%Y A321402 Cf. A000219, A007716, A059201, A302545, A316980, A316983, A319560, A319616.
%Y A321402 Cf. A320796, A320797, A320798, A320804, A320811, A320812, A321401, A321404, A321405, A321406, A321407.
%K A321402 nonn,more
%O A321402 0,5
%A A321402 _Gus Wiseman_, Nov 09 2018