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 A327013 #5 Dec 22 2019 19:13:27
%S A327013 1,2,3,6,23,282,28033
%N A327013 Number of non-isomorphic T_0 set-systems covering a subset of {1..n} that are closed under intersection.
%C A327013 A set-system is a finite set of finite nonempty sets. The dual of a set-system has, for each vertex, one edge consisting of the indices (or positions) of the edges containing that vertex. For example, the dual of {{1,2},{2,3}} is {{1},{1,2},{2}}. The T_0 condition means that the dual is strict (no repeated edges).
%e A327013 Non-isomorphic representatives of the a(1) = 2 through a(4) = 23 set-systems:
%e A327013 0 0 0 0
%e A327013 {1} {1} {1} {1}
%e A327013 {1}{12} {1}{12} {1}{12}
%e A327013 {1}{12}{13} {1}{12}{13}
%e A327013 {1}{12}{123} {1}{12}{123}
%e A327013 {1}{12}{13}{123} {1}{12}{13}{14}
%e A327013 {1}{12}{13}{123}
%e A327013 {1}{12}{13}{124}
%e A327013 {1}{12}{123}{124}
%e A327013 {1}{12}{13}{1234}
%e A327013 {1}{12}{123}{1234}
%e A327013 {1}{12}{13}{14}{123}
%e A327013 {1}{12}{13}{123}{124}
%e A327013 {1}{12}{13}{14}{1234}
%e A327013 {1}{12}{13}{123}{1234}
%e A327013 {1}{12}{13}{124}{1234}
%e A327013 {1}{12}{123}{124}{1234}
%e A327013 {1}{12}{13}{14}{123}{124}
%e A327013 {1}{12}{13}{14}{123}{1234}
%e A327013 {1}{12}{13}{123}{124}{1234}
%e A327013 {1}{12}{13}{14}{123}{124}{134}
%e A327013 {1}{12}{13}{14}{123}{124}{1234}
%e A327013 {1}{12}{13}{14}{123}{124}{134}{1234}
%Y A327013 The labeled version is A326959.
%Y A327013 T_0 set-systems are A326940.
%Y A327013 Cf. A051185, A059201, A319559, A309615, A319637, A326944, A326945, A326946.
%K A327013 nonn,more
%O A327013 0,2
%A A327013 _Gus Wiseman_, Dec 10 2019
%E A327013 a(5)-a(6) from _Andrew Howroyd_, Dec 21 2019