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 A306000 #10 Aug 12 2019 23:06:13
%S A306000 1,1,2,16,864,1150976,899934060544,291136684662192699604992,
%T A306000 14704020783497694096990514485197495566069661696,
%U A306000 12553242487939982849962414795232892198542733625222671042878037323112413463887484853594095616
%N A306000 Number of labeled intersecting set-systems with no singletons covering some subset of {1,...,n}.
%C A306000 An intersecting set-system S is a finite set of finite nonempty sets (edges), any two of which have a nonempty intersection. A singleton is an edge containing only one vertex.
%F A306000 a(n) = A051185(n) - n*2^(2^(n-1)-1). - _Andrew Howroyd_, Aug 12 2019
%e A306000 The a(3) = 16 set-systems:
%e A306000 {}
%e A306000 {{1,2}}
%e A306000 {{1,3}}
%e A306000 {{2,3}}
%e A306000 {{1,2,3}}
%e A306000 {{1,2},{1,3}}
%e A306000 {{1,2},{2,3}}
%e A306000 {{1,3},{2,3}}
%e A306000 {{1,2},{1,2,3}}
%e A306000 {{1,3},{1,2,3}}
%e A306000 {{2,3},{1,2,3}}
%e A306000 {{1,2},{1,3},{2,3}}
%e A306000 {{1,2},{1,3},{1,2,3}}
%e A306000 {{1,2},{2,3},{1,2,3}}
%e A306000 {{1,3},{2,3},{1,2,3}}
%e A306000 {{1,2},{1,3},{2,3},{1,2,3}}
%Y A306000 Cf. A001206, A006126, A051185, A048143, A058891, A305001, A305843, A305844, A305854-A305857, A305935, A305999, A306001.
%K A306000 nonn
%O A306000 0,3
%A A306000 _Gus Wiseman_, Jun 16 2018
%E A306000 a(6)-a(9) from _Andrew Howroyd_, Aug 12 2019