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 A316981 #6 Jul 18 2018 17:51:43 %S A316981 1,1,2,6,15,40,121 %N A316981 Number of non-isomorphic strict multiset partitions of weight n with no equivalent vertices. %C A316981 Also the number of nonnegative integer n X n matrices with sum of elements equal to n, under row and column permutations, with no equal rows and no equal columns. %C A316981 In a multiset partition, two vertices are equivalent if in every block the multiplicity of the first is equal to the multiplicity of the second. %e A316981 Non-isomorphic representatives of the a(3) = 6 strict multiset partitions with no equivalent vertices (first column) and their duals (second column): %e A316981 (111) <-> (111) %e A316981 (122) <-> (1)(11) %e A316981 (1)(11) <-> (122) %e A316981 (1)(22) <-> (1)(22) %e A316981 (2)(12) <-> (2)(12) %e A316981 (1)(2)(3) <-> (1)(2)(3) %Y A316981 Cf. A000009, A001055, A007716, A007717, A020555, A045778. %Y A316981 Cf. A316974, A316978, A316979, A316980, A316983. %K A316981 nonn,more %O A316981 0,3 %A A316981 _Gus Wiseman_, Jul 18 2018