

A051224


Number of ways of placing n nonattacking superqueens on n X n board (symmetric solutions count only once).


6



1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 6, 22, 239, 653, 4089, 25411, 166463, 1115871, 8062150, 61984976, 497236090, 4261538564, 38352532487, 360400504834, 3518014210402, 35752764285788
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OFFSET

1,11


COMMENTS

A superqueen moves like a queen and a knight.


LINKS

Table of n, a(n) for n=1..26.
D. Bill, Durango Bill's The NQueens Problem
W. Schubert, NQueens page  W. Schubert, Nov 29 2009


FORMULA

a(n) = (1/8) * (Q(n) + P(n) + 2 * R(n)), where Q(n) = A051223(n) [all solutions], P(n) [point symmetric solutions (180 degrees)] and R(n) [rotationally symmetric solutions (90 degrees)]. This formula has the same structure as the formula for A002562. There seem to be no OEIS sequences (yet) for P(n) and R(n). See http://m29s20.vlinux.de/~wschub/nqueen.html for a few terms.  W. Schubert, Nov 29 2009


CROSSREFS

Cf. A051223, A002562.
Sequence in context: A230964 A075811 A121796 * A062818 A154079 A160633
Adjacent sequences: A051221 A051222 A051223 * A051225 A051226 A051227


KEYWORD

nonn,more


AUTHOR

Ulrich Schimke (ulrschimke(AT)aol.com)


EXTENSIONS

a(20) from Bill link added Jul 25 2006
a(21)..a(22) added from Bill's website. Max Alekseyev, Oct 19 2008
Added formula and a(23)..a(25) derived by formula. W. Schubert, Nov 29 2009
Added a(26). W. Schubert, Jan 18 2011


STATUS

approved



