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 A322635 #17 Mar 09 2020 21:19:03
%S A322635 2,4,4,24,78,1908,23368,1961200,75942758,25703384940,4184912454930,
%T A322635 4462909435830552,2245354417775573206,10567193418810168583576,
%U A322635 24001585002447984453495392,348615956932626441906675011568,2412972383955442904868321667433106,162906453913051798826796439651249753404
%N A322635 Number of regular graphs with loops on n labeled vertices.
%C A322635 A graph is regular if all vertices have the same degree. A loop adds 2 to the degree of its vertex.
%H A322635 Wikipedia, <a href="https://en.wikipedia.org/wiki/Regular_graph">Regular graph</a>
%H A322635 Gus Wiseman, <a href="/A322635/a322635.png">The a(4) = 24 regular graphs with loops.</a>
%H A322635 Gus Wiseman, <a href="/A322635/a322635_1.png">The a(5) = 78 regular graphs with loops.</a>
%t A322635 Table[Sum[SeriesCoefficient[Product[1+Times@@x/@s,{s,Select[Tuples[Range[n],2],OrderedQ]}],Sequence@@Table[{x[i],0,k},{i,n}]],{k,0,2n}],{n,6}]
%o A322635 (PARI) for(n=1, 10, print1(A322635(n), ", ")) \\ See A295193 for script, _Andrew Howroyd_, Aug 28 2019
%Y A322635 Row sums of A333158.
%Y A322635 Cf. A000666, A054921, A059441, A295193, A299353, A306017, A306021, A319189, A319190, A319612, A322659, A322661.
%K A322635 nonn
%O A322635 1,1
%A A322635 _Gus Wiseman_, Dec 21 2018
%E A322635 a(11)-a(18) from _Andrew Howroyd_, Aug 28 2019