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 A297664 #12 Feb 16 2025 08:33:52 %S A297664 0,1,5,24,229,3436,65772,1743247,78586742,7234839185,1330059590925, %T A297664 421587920205546,212201572752086670,170288846375423693683, %U A297664 227570453486998336648738,527014715702923506908210573,2140337449056844246626590305042,15055309813180236733267168372538873 %N A297664 Number of chordless cycles in the n X n grid graph. %H A297664 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/ChordlessCycle.html">Chordless Cycle</a> %H A297664 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/GridGraph.html">Grid Graph</a> %Y A297664 Main diagonal of A360196. %Y A297664 Cf. A003763, A140517, A360200, A360914. %K A297664 nonn %O A297664 1,3 %A A297664 _Eric W. Weisstein_, Jan 02 2018 %E A297664 a(7)-a(18) from _Andrew Howroyd_, Jan 08 2018