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 A299353 #16 Jul 15 2018 13:21:33 %S A299353 1,1,1,5,50,1713,1101990,68715891672,1180735735356264714926, %T A299353 170141183460507906731293351306487161569, %U A299353 7237005577335553223087828975127304177495735363998991435497132228228565768846 %N A299353 Number of labeled connected uniform hypergraphs spanning n vertices. %C A299353 A hypergraph is uniform if all edges have the same size. %C A299353 Let T be the regular triangle A299354, where column k is the logarithmic transform of the inverse binomial transform of c(d) = 2^binomial(d,k). Then a(n) is the sum of row n. %H A299353 Wikipedia, <a href="http://en.wikipedia.org/wiki/Hypergraph">Hypergraph</a> %e A299353 The a(3) = 5 hypergraphs: %e A299353 {{1,2,3}} %e A299353 {{1,2},{1,3}} %e A299353 {{1,2},{2,3}} %e A299353 {{1,3},{2,3}} %e A299353 {{1,2},{1,3},{2,3}} %t A299353 nn=10;Table[Sum[SeriesCoefficient[Log[Sum[x^m/m!*(-1)^(m-d)*Binomial[m,d]*2^Binomial[d,k],{m,0,n},{d,0,m}]],{x,0,n}]*n!,{k,n}],{n,nn}] %Y A299353 Cf. A000005, A001315, A006126, A006129, A038041, A048143, A298422, A299354, A299471, A306020, A306021. %K A299353 nonn %O A299353 0,4 %A A299353 _Gus Wiseman_, Jun 18 2018