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 A068940 #23 Feb 16 2025 08:32:45 %S A068940 1,1,4,7,13,21,32,48,67,91,121,133,169 %N A068940 Maximum number of chess queens that can be placed on a 3-dimensional chessboard of order n so that no two queens attack each other. %H A068940 <a href="http://web.archive.org/web/20050316123203/http://members.aol.com/Bitzenbeitz/Contests/AttackingQueens/Description.html">Attacking Queens Programming Contest</a>, Description of the contest. %H A068940 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/IndependenceNumber.html">Independence Number</a>. %H A068940 Al Zimmermann, <a href="http://recmath.com/contest/AttackingQueens/FinalReport.html">Attacking Queens Programming Contest</a>, Final report, 2002. %H A068940 <a href="http://groups.yahoo.com/group/AttackingQueens/database">Attacking Queens Programming Contest Database</a> [broken link] %Y A068940 Cf. A068941, A115992, A375103. %K A068940 nonn,more,hard %O A068940 1,3 %A A068940 _Al Zimmermann_, Mar 08 2002