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 A321228 #6 Nov 01 2018 11:37:44
%S A321228 1,1,1,2,4,6,13,23,49,100,220
%N A321228 Number of non-isomorphic hypertrees of weight n with singletons.
%C A321228 A hypertree with singletons is a connected set system (finite set of finite nonempty sets) with density -1, where the density of a set system is the sum of sizes of the parts (weight) minus the number of parts minus the number of vertices.
%e A321228 Non-isomorphic representatives of the a(1) = 1 through a(7) = 23 hypertrees:
%e A321228 {{1}} {{1,2}} {{1,2,3}} {{1,2,3,4}} {{1,2,3,4,5}}
%e A321228 {{2},{1,2}} {{1,3},{2,3}} {{1,4},{2,3,4}}
%e A321228 {{3},{1,2,3}} {{4},{1,2,3,4}}
%e A321228 {{1},{2},{1,2}} {{2},{1,3},{2,3}}
%e A321228 {{2},{3},{1,2,3}}
%e A321228 {{3},{1,3},{2,3}}
%e A321228 .
%e A321228 {{1,2,3,4,5,6}} {{1,2,3,4,5,6,7}}
%e A321228 {{1,2,5},{3,4,5}} {{1,2,6},{3,4,5,6}}
%e A321228 {{1,5},{2,3,4,5}} {{1,6},{2,3,4,5,6}}
%e A321228 {{5},{1,2,3,4,5}} {{6},{1,2,3,4,5,6}}
%e A321228 {{1},{1,4},{2,3,4}} {{1},{1,5},{2,3,4,5}}
%e A321228 {{1,3},{2,4},{3,4}} {{1,2},{2,5},{3,4,5}}
%e A321228 {{1,4},{2,4},{3,4}} {{1,4},{2,5},{3,4,5}}
%e A321228 {{3},{1,4},{2,3,4}} {{1,5},{2,5},{3,4,5}}
%e A321228 {{3},{4},{1,2,3,4}} {{4},{1,2,5},{3,4,5}}
%e A321228 {{4},{1,4},{2,3,4}} {{4},{1,5},{2,3,4,5}}
%e A321228 {{1},{2},{1,3},{2,3}} {{4},{5},{1,2,3,4,5}}
%e A321228 {{1},{2},{3},{1,2,3}} {{5},{1,2,5},{3,4,5}}
%e A321228 {{2},{3},{1,3},{2,3}} {{5},{1,5},{2,3,4,5}}
%e A321228 {{1},{3},{1,4},{2,3,4}}
%e A321228 {{1},{4},{1,4},{2,3,4}}
%e A321228 {{2},{1,3},{2,4},{3,4}}
%e A321228 {{2},{3},{1,4},{2,3,4}}
%e A321228 {{2},{3},{4},{1,2,3,4}}
%e A321228 {{3},{1,4},{2,4},{3,4}}
%e A321228 {{3},{4},{1,4},{2,3,4}}
%e A321228 {{4},{1,3},{2,4},{3,4}}
%e A321228 {{4},{1,4},{2,4},{3,4}}
%e A321228 {{1},{2},{3},{1,3},{2,3}}
%Y A321228 Cf. A000272, A007716, A007718, A030019, A052888, A134954, A304867, A304887, A317672, A318697, A321155, A321227, A321229.
%K A321228 nonn,more
%O A321228 0,4
%A A321228 _Gus Wiseman_, Oct 31 2018