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 A305855 #14 May 11 2020 09:43:21
%S A305855 1,1,1,3,9,72,3441,47170585
%N A305855 Number of unlabeled spanning intersecting antichains on n vertices.
%C A305855 An intersecting antichain S is a finite set of finite nonempty sets (edges), any two of which have a nonempty intersection, and none of which is a subset of any other. S is spanning if every vertex is contained in some edge.
%F A305855 a(n) = A305857(n) - A305857(n-1) for n > 0. - _Andrew Howroyd_, Aug 13 2019
%e A305855 Non-isomorphic representatives of the a(4) = 9 spanning intersecting antichains:
%e A305855 {{1,2,3,4}}
%e A305855 {{1,4},{2,3,4}}
%e A305855 {{1,3,4},{2,3,4}}
%e A305855 {{1,2},{1,3,4},{2,3,4}}
%e A305855 {{1,3},{1,4},{2,3,4}}
%e A305855 {{1,4},{2,4},{3,4}}
%e A305855 {{1,2,4},{1,3,4},{2,3,4}}
%e A305855 {{1,2},{1,3},{1,4},{2,3,4}}
%e A305855 {{1,2,3},{1,2,4},{1,3,4},{2,3,4}}
%Y A305855 Cf. A001206, A006126, A051185, A261006, A283877, A304998, A305843, A305844, A305854-A305857.
%K A305855 nonn,more
%O A305855 0,4
%A A305855 _Gus Wiseman_, Jun 11 2018
%E A305855 a(6) from _Andrew Howroyd_, Aug 13 2019
%E A305855 a(7) from _Brendan McKay_, May 11 2020