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 A187236 #12 Feb 16 2025 08:33:14 %S A187236 0,0,0,0,1,8,138,3459,137912,8735904,903185866,159235673397, %T A187236 50091451190693 %N A187236 Number of simple imperfect graphs on n vertices. %H A187236 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/ImperfectGraph.html">Imperfect Graph.</a> %F A187236 a(n) = A000088(n) - A052431(n). %Y A187236 Cf. A000088, A052431, A187237. %K A187236 nonn,more,hard %O A187236 1,6 %A A187236 _Eric W. Weisstein_, Mar 07 2011 %E A187236 a(13) from _Alois P. Heinz_, Aug 14 2019