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 A019654 #32 Feb 16 2025 08:32:33 %S A019654 0,1,1,1,3,40,655,16573 %N A019654 Consider problem of placing N queens on an n X n board so that each queen attacks precisely k others. Here k=4 and sequence gives number of different solutions when N takes its maximal value. %C A019654 I would also like to get the sequences that give the maximal value of N. %C A019654 Maximal values given by A063724. - _Sean A. Irvine_, Mar 31 2019 %C A019654 Values for a(9) onwards currently unverified. - _Sean A. Irvine_, Apr 05 2019 %D A019654 M. Gardner, The Last Recreations, Springer, 1997, p. 282. %D A019654 M. Gardner, The Colossal Book of Mathematics, 2001, p. 209. %H A019654 Sean A. Irvine, <a href="/A019654/a019654.pdf">Solutions for n<=8</a> %H A019654 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/QueensProblem.html">Queens Problem</a> [From Claudio (lordofchaos000(AT)hotmail.com), May 31 2010] %Y A019654 Cf. A051567-A051571, A051754-A051759, A063724. %K A019654 nonn,nice,more %O A019654 3,5 %A A019654 _N. J. A. Sloane_, Oct 03 2002 %E A019654 I am not certain this description is correct, nor how rigorous the results are. %E A019654 a(4) and a(5) changed to 1 and irrelevant comment removed by _Sean A. Irvine_, Apr 02 2019