A189853 Number of ways to place n nonattacking composite pieces rook + rider[1,6] on an n X n chessboard.

1, 2, 6, 24, 120, 720, 2640, 13596, 87768, 680274, 6090756, 61678252, 482005340, 4454053680, 46705656280, 549750105234

Offset

1,2

Comments

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

Links

Table of n, a(n) for n=1..16.

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, A189852

Sequence in context: A276840 A364426 A178011 * A189857 A189860 A274795

Adjacent sequences: A189850 A189851 A189852 * A189854 A189855 A189856

Keyword

nonn,hard

Author

Vaclav Kotesovec, Apr 29 2011

Status

approved