A189866 Number of ways to place n nonattacking composite pieces queen + leaper[1,5] on an n X n chessboard.

1, 0, 0, 2, 10, 0, 0, 0, 40, 52, 160, 500, 2656, 11540, 67776, 415716, 2610520, 17450592, 124903880, 944965832, 7292031780

Offset

1,4

Comments

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

Links

Table of n, a(n) for n=1..21.

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, A189865, A189564

Sequence in context: A189876 A189867 A189875 * A364253 A189874 A189865

Adjacent sequences: A189863 A189864 A189865 * A189867 A189868 A189869

Keyword

nonn,hard

Author

Vaclav Kotesovec, Apr 29 2011

Status

approved