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 A330464 #7 Feb 28 2020 12:55:01
%S A330464 1,1,3,9,32,111,463,1942
%N A330464 Number of non-isomorphic weight-n sets of set-systems with distinct multiset unions.
%C A330464 A set-system is a finite set of finite nonempty sets of positive integers.
%C A330464 As an alternative description, a(n) is the number of non-isomorphic sets of sets of sets with n leaves where the inner sets of sets all have different multiset unions.
%e A330464 Non-isomorphic representatives of the a(1) = 1 through a(3) = 9 sets:
%e A330464 {} {{{1}}} {{{1,2}}} {{{1,2,3}}}
%e A330464 {{{1},{2}}} {{{1},{1,2}}}
%e A330464 {{{1}},{{2}}} {{{1},{2,3}}}
%e A330464 {{{1}},{{1,2}}}
%e A330464 {{{1}},{{2,3}}}
%e A330464 {{{1},{2},{3}}}
%e A330464 {{{1}},{{1},{2}}}
%e A330464 {{{1}},{{2},{3}}}
%e A330464 {{{1}},{{2}},{{3}}}
%Y A330464 Non-isomorphic sets of sets are A283877.
%Y A330464 Non-isomorphic sets of sets of sets are A323790.
%Y A330464 Non-isomorphic set partitions of set-systems are A323795.
%Y A330464 Cf. A089259, A141268, A271619, A279375, A279785, A306186, A316980, A317533, A318564, A318565, A318566, A330459, A330472.
%K A330464 nonn,more
%O A330464 0,3
%A A330464 _Gus Wiseman_, Dec 26 2019