cp's OEIS Frontend

A051223 Number of ways of placing n nonattacking superqueens on an n X n board.

%I A051223 #49 Jan 22 2024 09:08:32
%S A051223 1,0,0,0,0,0,0,0,0,4,44,156,1876,5180,32516,202900,1330622,8924976,
%T A051223 64492432,495864256,3977841852,34092182276,306819842212,2883202816808,
%U A051223 28144109776812,286022102245804
%N A051223 Number of ways of placing n nonattacking superqueens on an n X n board.
%C A051223 A superqueen moves like a queen and a knight.
%C A051223 A linear-time algorithm giving an explicit solution for any n >= 10 for the n-super-queens-problem can be found at the link. Included is an online solver, implemented in JavaScript. - Frank Schwellinger (nummer_eins(AT)web.de), Mar 19 2004. [But see the next comment - _N. J. A. Sloane_, Jul 01 2021]
%C A051223 Escamocher and O'Sullivan (2021) claim Schwellinger's algorithm is incorrect, and that their own algorithm is the first published linear-time algorithm. - _N. J. A. Sloane_, Jul 01 2021
%H A051223 D. Bill, <a href="http://www.durangobill.com/N_Queens.html">Durango Bill's The N-Queens Problem</a>
%H A051223 Guillaume Escamocher and Barry O'Sullivan, <a href="https://doi.org/10.1016/j.disc.2021.112316">Leprechauns on the chessboard</a>, Discrete Mathematics, 344(5), 2021. See especially page 3.
%H A051223 Vaclav Kotesovec, <a href="https://oeis.org/wiki/User:Vaclav_Kotesovec">Non-attacking chess pieces</a>, 6ed.
%H A051223 R. Oprisch, <a href="http://oprisch.net/SuperQueens/SuperQueens.html">N x N SuperQueens Solutions Table</a>
%H A051223 F. Schwellinger, <a href="https://web.archive.org/web/20050317085130/http://super.info.ms/">Explicit Solution To the N-Super-Queens Problem</a>.
%H A051223 W. Schubert, <a href="https://web.archive.org/web/20160410085823/http://m29s20.vlinux.de/~wschub/nqueen.html">N-Queens page</a>
%Y A051223 Cf. A051224, A000170.
%K A051223 nonn,nice,more
%O A051223 1,10
%A A051223 Ulrich Schimke (ulrschimke(AT)aol.com)
%E A051223 a(20) from Bill link added Jul 25 2006
%E A051223 a(21)-a(23) from R. Oprisch's website added by _Max Alekseyev_, Sep 29 2006
%E A051223 a(24)-a(26) from _W. Schubert_, Jul 31 2009, Nov 29 2009, Jan 18 2011