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 A319612 #23 Sep 02 2019 23:04:09
%S A319612 1,0,1,1,7,13,171,931,45935,1084413,155862511,10382960971,
%T A319612 6939278572095,2203360500122299,4186526756621772343,
%U A319612 3747344008241368443819,35041787059691023579970847,156277111373303386104606663421,4142122641757598618318165240180095
%N A319612 Number of regular simple graphs spanning n vertices.
%C A319612 A graph is regular if all vertices have the same degree. The span of a graph is the union of its edges.
%F A319612 a(n) = A295193(n) - 1.
%e A319612 The a(4) = 7 edge-sets:
%e A319612 {{1,2},{3,4}}
%e A319612 {{1,3},{2,4}}
%e A319612 {{1,4},{2,3}}
%e A319612 {{1,2},{1,3},{2,4},{3,4}}
%e A319612 {{1,2},{1,4},{2,3},{3,4}}
%e A319612 {{1,3},{1,4},{2,3},{2,4}}
%e A319612 {{1,2},{1,3},{1,4},{2,3},{2,4},{3,4}}
%Y A319612 Cf. A002829, A005176, A110100, A116539, A295193, A306017, A319189, A319190.
%K A319612 nonn
%O A319612 0,5
%A A319612 _Gus Wiseman_, Dec 17 2018
%E A319612 a(16)-a(18) from _Andrew Howroyd_, Sep 02 2019