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 A084270 #12 Feb 16 2025 08:32:49 %S A084270 0,1,6,40,375,5176,103236,2922445,116011230,6433447396,498234407451, %T A084270 54007795331920,8213123246906760,1756336596363006841, %U A084270 528975889250504033526,224688018516023267969440,134708289561117007261966815 %N A084270 Number of labeled 2-chromatic (i.e., chromatic number = 2) graphs on n nodes. %H A084270 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/n-ChromaticGraph.html">n-Chromatic Graph</a> %F A084270 a(n) = A047864(n)-1. - _Vladeta Jovovic_, Jul 31 2003 %Y A084270 Cf. A084271, A084272. %K A084270 nonn %O A084270 1,3 %A A084270 _Eric W. Weisstein_, May 24 2003 %E A084270 More terms from _Vladeta Jovovic_, Jul 31 2003 %E A084270 One further term from _David Wasserman_, Dec 13 2004