A189850 Number of ways to place n nonattacking composite pieces rook + rider[1,3] on an n X n chessboard.

1, 2, 6, 8, 24, 126, 316, 1344, 7782, 33930, 172430, 1106754, 6432236, 45188572, 372437930, 2728674526, 23648822368, 233010291526, 2083328647344

Offset: 1

Author

Vaclav Kotesovec, Apr 29 2011

Keywords

• nonn
• hard

Comments

In fairy chess, the rider [1,3] is called a Camelrider.

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

Links

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

Crossrefs

Cf. A000170, A189837