

A189869


Number of ways to place n nonattacking composite pieces queen + leaper[2,5] on an n X n chessboard.


2



1, 0, 0, 2, 10, 4, 28, 20, 56, 72, 288, 1304, 6368, 22884, 125864, 755412, 4565572, 29862256, 207238124, 1540506028, 11774180220
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OFFSET

1,4


COMMENTS

a(n) is also number of permutations p of 1,2,...,n satisfying p(i+2)p(i)<>5 AND p(j+5)p(j)<>2 AND p(m+k)p(m)<>k for all i>=1, j>=1, m>=1, k>=1, i+2<=n, j+5<=n, m+k<=n


LINKS

Table of n, a(n) for n=1..21.
V. Kotesovec, Number of ways of placing nonattacking queens, kings, bishops and knights (in English and Czech)
Wikipedia, Fairy chess piece


CROSSREFS

Cf. A051223, A189866, A189867, A189868, A189567
Sequence in context: A189872 A199832 A189878 * A054790 A140393 A000170
Adjacent sequences: A189866 A189867 A189868 * A189870 A189871 A189872


KEYWORD

nonn,hard


AUTHOR

Vaclav Kotesovec, Apr 29 2011


STATUS

approved



