A189862 Number of ways to place n nonattacking composite pieces rook + rider[4,6] on an n X n chessboard.

1, 2, 6, 24, 120, 720, 3720, 22336, 153796, 1213344, 10849504, 108891704, 1023690268, 10593791168, 119694887008, 1472935989952

Offset: 1

Author

Vaclav Kotesovec, Apr 29 2011

Keywords

• nonn
• hard

Comments

a(n) is also number of permutations p of 1,2,...,n satisfying |p(i+4k)-p(i)|<>6k AND |p(j+6k)-p(j)|<>4k for all i>=1, j>=1, k>=1, i+4k<=n, j+6k<=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, A189853, A189857, A189860