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 A215621 #16 Feb 16 2025 08:33:18 %S A215621 0,0,0,0,1,13,204,4700,147063,5669609 %N A215621 Number of nonplanar apex graphs on n vertices. %H A215621 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/ApexGraph.html">Apex Graph</a> %H A215621 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/NonplanarGraph.html">Nonplanar Graph</a> %Y A215621 Cf. A215620 (counts of all apex graphs, including planar ones). %K A215621 nonn,more %O A215621 1,6 %A A215621 _Eric W. Weisstein_, Aug 17 2012 %E A215621 a(10) from _Eric W. Weisstein_, Aug 20 2012