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A051223
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Number of ways of placing n nonattacking superqueens on an n X n board.
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24
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1, 0, 0, 0, 0, 0, 0, 0, 0, 4, 44, 156, 1876, 5180, 32516, 202900, 1330622, 8924976, 64492432, 495864256, 3977841852, 34092182276, 306819842212, 2883202816808, 28144109776812, 286022102245804
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OFFSET
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1,10
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COMMENTS
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A superqueen moves like a queen and a knight.
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]
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
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LINKS
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CROSSREFS
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KEYWORD
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nonn,nice,more
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AUTHOR
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Ulrich Schimke (ulrschimke(AT)aol.com)
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EXTENSIONS
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a(20) from Bill link added Jul 25 2006
a(21)-a(23) from R. Oprisch's website added by Max Alekseyev, Sep 29 2006
a(24)-a(26) from W. Schubert, Jul 31 2009, Nov 29 2009, Jan 18 2011
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STATUS
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approved
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