A189860 Number of ways to place n nonattacking composite pieces rook + rider[3,6] on an n X n chessboard.

1, 2, 6, 24, 120, 720, 3312, 18688, 127104, 990208, 8878016, 89267712, 789509184, 7803741824, 85447337472, 1008717911040

Offset

1,2

Comments

a(n) is also number of permutations p of 1,2,...,n satisfying |p(i+3k)-p(i)|<>6k AND |p(j+6k)-p(j)|<>3k for all i>=1, j>=1, k>=1, i+3k<=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, A189853, A189857

Sequence in context: A178011 A189853 A189857 * A274795 A174702 A173846

Adjacent sequences: A189857 A189858 A189859 * A189861 A189862 A189863

Keyword

nonn,hard

Author

Vaclav Kotesovec, Apr 29 2011

Status

approved