A189852 Number of ways to place n nonattacking composite pieces rook + rider[1,5] on an n X n chessboard.

1, 2, 6, 24, 120, 336, 1474, 8340, 57756, 475658, 2812910, 20852460, 181255892, 1817101242, 20435345782, 197871434994

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+k)-p(i)|<>5k AND |p(j+5k)-p(j)|<>k for all i>=1, j>=1, k>=1, i+k<=n, j+5k<=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, A189850, A189851