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 A093352 #23 Apr 05 2022 21:10:40
%S A093352 1,1,1,5,55,959,31883,2076383,267530657,68644357201,35172312944057,
%T A093352 36025019516955853,73784654524456043287,302228644804839247744495,
%U A093352 2475873364061564307502565395,40564787473148108729970731074007,1329227698679709317077126629247388161
%N A093352 Number of labeled n-vertex graphs without a 2-component.
%H A093352 Alois P. Heinz, <a href="/A093352/b093352.txt">Table of n, a(n) for n = 0..50</a>
%F A093352 E.g.f.: exp(-x^2/2)*Sum_{n>=0} 2^binomial(n,2)*x^n/n!.
%F A093352 a(n) = n!*Sum_{q=0..floor(n/2)} ((-1)^q/(2^q*q!))*(2^C(n-2*q,2)/(n-2*q)!). - _Marko Riedel_, Apr 05 2022
%p A093352 A093352 := n -> n!*add((-1)^q/2^q/q!*2^binomial(n-2*q,2)/(n-2*q)!, q=0..floor(n/2)); # _Marko Riedel_, Apr 05 2022
%t A093352 nn = 15; g = Sum[2^Binomial[n, 2] x^n/n!, {n, 0, nn}];
%t A093352 Range[0, nn]! CoefficientList[Series[g/Exp[x^2/2], {x, 0, nn}], x] (* _Geoffrey Critzer_, Aug 27 2013 *)
%Y A093352 Cf. A093351, A006129.
%K A093352 nonn
%O A093352 0,4
%A A093352 Goran Kilibarda, _Vladeta Jovovic_, Apr 26 2004