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 A084272 #13 Feb 16 2025 08:32:49 %S A084272 0,0,0,1,65,5042,605545,120653315,40885736829,23907349095479, %T A084272 24391928745798217 %N A084272 Number of labeled 4-chromatic (i.e., chromatic number = 4) graphs on n nodes. %H A084272 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/n-ChromaticGraph.html">n-Chromatic Graph</a> %F A084272 a(n) = A084280(n) - A084279(n). - _Andrew Howroyd_, Dec 02 2018 %Y A084272 Cf. A084270, A084271, A084279, A084280. %K A084272 nonn,more %O A084272 1,5 %A A084272 _Eric W. Weisstein_, May 24 2003 %E A084272 a(7)-a(11) from _Andrew Howroyd_, Dec 02 2018