A189867 Number of ways to place n nonattacking composite pieces queen + leaper[2,3] on an n X n chessboard.

1, 0, 0, 2, 10, 0, 0, 0, 0, 48, 152, 472, 2696, 12320, 74436, 429620, 2515116, 16122496, 113016608, 843492920, 6575649316, 54694203188

Offset

1,4

Comments

In fairy chess the leaper [2,3] is called a zebra.

a(n) is also number of permutations p of 1,2,...,n satisfying |p(i+2)-p(i)|<>3 AND |p(j+3)-p(j)|<>2 AND |p(m+k)-p(m)|<>k for all i>=1, j>=1, m>=1, k>=1, i+2<=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, A189864, A189565

Sequence in context: A050924 A181500 A189876 * A189875 A189866 A364253

Adjacent sequences: A189864 A189865 A189866 * A189868 A189869 A189870

Keyword

nonn,hard

Author

Vaclav Kotesovec, Apr 29 2011

Status

approved