A189840 Number of ways to place n nonattacking composite pieces rook + rider[4,4] on an n X n chessboard.

1, 2, 6, 24, 108, 544, 3264, 23040, 171072, 1409664, 12916224, 131217408, 1428028032, 16709309440, 210367491840, 2847184825728

Offset

1,2

Comments

a(n) is also number of permutations p of 1,2,...,n satisfying |p(j+4k)-p(j)|<>4k for all j>=1, k>=1, j+4k<=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. A189255, A000170, A189838, A189839

Sequence in context: A094433 A178594 A277248 * A189255 A324591 A338987

Adjacent sequences: A189837 A189838 A189839 * A189841 A189842 A189843

Keyword

nonn,hard

Author

Vaclav Kotesovec, Apr 29 2011

Status

approved