A189864 Number of ways to place n nonattacking composite pieces queen + leaper[1,3] on an n X n chessboard.

1, 0, 0, 0, 0, 0, 0, 0, 0, 4, 56, 176, 1932, 4188, 26960, 182456, 1132064, 7645784, 58695136, 470822912, 3792417988, 32440237692

Offset

1,10

Comments

(In fairy chess, the leaper [1,3] is called a camel.)

a(n) is also the number of permutations p of 1,2,...,n satisfying |p(i+1) - p(i)| <> 3 AND |p(j+3) - p(j)| <> 1 AND |p(m+k) - p(m)| <> k for all i >= 1, j >= 1, m >= 1, k >= 1, i+1 <= n, j+3 <= n, m+k <= n.

Links

Table of n, a(n) for n=1..22.

V. Kotesovec, Number of ways of placing non-attacking queens, kings, bishops and knights (in English and Czech).

Wikipedia, Fairy chess piece.

Crossrefs

Cf. A051223, A189358.

Sequence in context: A143650 A143649 A168133 * A360262 A192845 A144138

Adjacent sequences: A189861 A189862 A189863 * A189865 A189866 A189867

Keyword

nonn,hard

Author

Vaclav Kotesovec, Apr 29 2011

Status

approved