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 A320811 #7 Nov 09 2018 07:56:18
%S A320811 1,0,1,2,7,21,57,200,575,1898,5893
%N A320811 Number of non-isomorphic multiset partitions with no singletons of aperiodic multisets of size n.
%C A320811 Also the number of nonnegative integer matrices up to row and column permutations with sum of elements equal to n and no zero rows or columns, in which (1) the row sums are all > 1 and (2) the column sums are relatively prime.
%C A320811 A multiset is aperiodic if its multiplicities are relatively prime.
%C A320811 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 A320811 Non-isomorphic representatives of the a(2) = 1 through a(5) = 21 multiset partitions:
%e A320811 {{1,2}} {{1,2,2}} {{1,2,2,2}} {{1,1,2,2,2}}
%e A320811 {{1,2,3}} {{1,2,3,3}} {{1,2,2,2,2}}
%e A320811 {{1,2,3,4}} {{1,2,2,3,3}}
%e A320811 {{1,2},{2,2}} {{1,2,3,3,3}}
%e A320811 {{1,2},{3,3}} {{1,2,3,4,4}}
%e A320811 {{1,2},{3,4}} {{1,2,3,4,5}}
%e A320811 {{1,3},{2,3}} {{1,1},{1,2,2}}
%e A320811 {{1,1},{2,2,2}}
%e A320811 {{1,1},{2,3,3}}
%e A320811 {{1,1},{2,3,4}}
%e A320811 {{1,2},{1,2,2}}
%e A320811 {{1,2},{2,2,2}}
%e A320811 {{1,2},{2,3,3}}
%e A320811 {{1,2},{3,3,3}}
%e A320811 {{1,2},{3,4,4}}
%e A320811 {{1,2},{3,4,5}}
%e A320811 {{1,3},{2,3,3}}
%e A320811 {{1,4},{2,3,4}}
%e A320811 {{2,2},{1,2,2}}
%e A320811 {{2,3},{1,2,3}}
%e A320811 {{3,3},{1,2,3}}
%Y A320811 Cf. A000740, A000837, A007716, A007916, A100953, A301700, A302545, A303386, A303546, A303707, A303708, A320797-A320813, A321283, A321390.
%K A320811 nonn,more
%O A320811 0,4
%A A320811 _Gus Wiseman_, Nov 08 2018