A189841 Number of ways to place n nonattacking composite pieces rook + rider[5,5] on an n X n chessboard.

1, 2, 6, 24, 120, 672, 4128, 28992, 231936, 2088960, 20017152, 207208704, 2326900992, 28338241536, 373152276480, 5206300028928

Offset

1,2

Comments

a(n) is also number of permutations p of 1,2,...,n satisfying |p(j+5k)-p(j)|<>5k for all j>=1, k>=1, j+5k<=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. A189256, A000170, A189838, A189839, A189840

Sequence in context: A152343 A177529 A138619 * A189256 A152344 A152340

Adjacent sequences: A189838 A189839 A189840 * A189842 A189843 A189844

Keyword

nonn,hard

Author

Vaclav Kotesovec, Apr 29 2011

Status

approved