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 A002565 M1313 N0502 #29 Dec 25 2017 11:58:13 %S A002565 0,2,5,3,15,150,5,56,3,39,681 %N A002565 Number of non-isomorphic ways to attack all squares on an n X n chessboard using the smallest possible number of queens with each queen attacking at least one other. %C A002565 Differs from A002563 and A002567 in that each queen is attacking at least one other queen. - _Sean A. Irvine_, Apr 05 2014 %C A002565 The Sainte-Laguë paper has "a(6)=140?". - _Sean A. Irvine_, Apr 05 2014 %D A002565 W. Ahrens, Mathematische Unterhaltungen und Spiele, second edition (1910), Vol. 1, p. 301. %D A002565 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence). %D A002565 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %H A002565 M. A. Sainte-Laguë, <a href="https://eudml.org/doc/192551">Les Réseaux (ou Graphes)</a>, Mémorial des Sciences Mathématiques, Fasc. 18, Gauthier-Villars, Paris, 1923, 64 pages. See p. 49. %H A002565 M. A. Sainte-Laguë, <a href="/A002560/a002560.pdf">Les Réseaux (ou Graphes)</a>, Mémorial des Sciences Mathématiques, Fasc. 18, Gauthier-Villars, Paris, 1923, 64 pages. See p. 49. [Incomplete annotated scan of title page and pages 18-51] %Y A002565 Cf. A002566 (all solutions for attacking queens). - _Sean A. Irvine_, Apr 05 2014 %K A002565 nonn,more %O A002565 1,2 %A A002565 _N. J. A. Sloane_ %E A002565 a(6) corrected and a(9)-a(11) from _Sean A. Irvine_, Apr 05 2014 %E A002565 Better name from _Sean A. Irvine_, Apr 05 2014