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 A327199 #5 Sep 01 2019 22:04:21
%S A327199 1,1,1,1,4,56,1031,27189,1165424,89723096,13371146135,3989665389689,
%T A327199 2388718032951812,2852540291841718752,6768426738881535155247,
%U A327199 31870401029679493862010949,297787425565749788134314214272
%N A327199 Number of labeled simple graphs with n vertices whose edge-set is not connected.
%C A327199 Also graphs with non-spanning edge-connectivity 0.
%F A327199 Binomial transform of A327070.
%e A327199 The a(4) = 4 edge-sets: {}, {12,34}, {13,24}, {14,23}.
%t A327199 csm[s_]:=With[{c=Select[Subsets[Range[Length[s]],{2}],Length[Intersection@@s[[#]]]>0&]},If[c=={},s,csm[Sort[Append[Delete[s,List/@c[[1]]],Union@@s[[c[[1]]]]]]]]];
%t A327199 Table[Length[Select[Subsets[Subsets[Range[n],{2}]],Length[csm[#]]!=1&]],{n,0,5}]
%Y A327199 Column k = 0 of A327148.
%Y A327199 The covering case is A327070.
%Y A327199 The unlabeled version is A327235.
%Y A327199 Cf. A001187, A006129, A322395, A326787, A327075, A327076, A327079, A327129, A327200, A327201, A327231, A327236.
%K A327199 nonn
%O A327199 0,5
%A A327199 _Gus Wiseman_, Sep 01 2019