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 A306006 #9 May 04 2025 15:37:08
%S A306006 1,1,1,2,3,5,10,16,30,57,109,209,431,873,1850,3979,8819,19863
%N A306006 Number of non-isomorphic intersecting set-systems of weight n.
%C A306006 An intersecting set-system S is a finite set of finite nonempty sets (edges), any two of which have a nonempty intersection. The weight of S is the sum of cardinalities of its elements. Weight is generally not the same as number of vertices.
%e A306006 Non-isomorphic representatives of the a(6) = 10 set-systems:
%e A306006 {{1,2,3,4,5,6}}
%e A306006 {{5},{1,2,3,4,5}}
%e A306006 {{1,5},{2,3,4,5}}
%e A306006 {{3,4},{1,2,3,4}}
%e A306006 {{1,2,5},{3,4,5}}
%e A306006 {{1,3,4},{2,3,4}}
%e A306006 {{3},{2,3},{1,2,3}}
%e A306006 {{4},{1,4},{2,3,4}}
%e A306006 {{1,2},{1,3},{2,3}}
%e A306006 {{1,4},{2,4},{3,4}}
%Y A306006 Cf. A007716, A034691, A048143, A049311, A116540, A283877, A293606, A293607, A304867, A305999, A305854-A305857, A306005-A306008.
%K A306006 nonn,more
%O A306006 0,4
%A A306006 _Gus Wiseman_, Jun 16 2018
%E A306006 a(10)-a(17) from _Bert Dobbelaere_, May 04 2025