A189863 Number of ways to place n nonattacking composite pieces rook + rider[5,6] on an n X n chessboard.

1, 2, 6, 24, 120, 720, 4176, 26140, 185084, 1491098, 13285034, 132514356, 1321161252, 14181339764, 164574628260, 2057033314380

Offset

1,2

Comments

a(n) is also number of permutations p of 1,2,...,n satisfying |p(i+5k)-p(i)|<>6k AND |p(j+6k)-p(j)|<>5k for all i>=1, j>=1, k>=1, i+5k<=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, A189860, A189862

Sequence in context: A173846 A154654 A189862 * A293776 A179343 A179347

Adjacent sequences: A189860 A189861 A189862 * A189864 A189865 A189866

Keyword

nonn,hard

Author

Vaclav Kotesovec, Apr 29 2011

Status

approved