A189865 Number of ways to place n nonattacking composite pieces queen + leaper[1,4] on an n X n chessboard.

1, 0, 0, 2, 10, 0, 0, 4, 32, 76, 196, 632, 3368, 12532, 79788, 468286, 2815088, 18287968, 126620984, 938037664, 7232141830, 59774887344

Offset

1,4

Comments

In fairy chess the leaper [1,4] is called a giraffe.

a(n) is also number of permutations p of 1,2,...,n satisfying |p(i+1)-p(i)|<>4 AND |p(j+4)-p(j)|<>1 AND |p(m+k)-p(m)|<>k for all i>=1, j>=1, m>=1, k>=1, i+1<=n, j+4<=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, A189864, A189563

Sequence in context: A189866 A364253 A189874 * A189880 A189871 A096877

Adjacent sequences: A189862 A189863 A189864 * A189866 A189867 A189868

Keyword

nonn,hard

Author

Vaclav Kotesovec, Apr 29 2011

Status

approved