A189881 Number of ways to place n nonattacking composite pieces queen + rider[4,5] on an n X n chessboard.

1, 0, 0, 2, 10, 4, 12, 32, 96, 144, 528, 1712, 7472, 24500, 103536, 486020, 2218808, 11113020, 59242576, 342584556, 1981826412

Offset

1,4

Comments

a(n) is also number of permutations p of 1,2,...,n satisfying |p(i+4k)-p(i)|<>5k AND |p(j+5k)-p(j)|<>4k AND |p(m+k)-p(m)|<>k for all i>=1, j>=1, m>=1, k>=1, i+4k<=n, j+5k<=n, m+k<=n

Links

Table of n, a(n) for n=1..21.

V. Kotesovec, Number of ways of placing non-attacking queens, kings, bishops and knights (in English and Czech)

Wikipedia, Fairy chess piece

Crossrefs

Cf. A102388, A189875, A189878, A189880, A189861

Sequence in context: A344794 A196364 A029673 * A189872 A319407 A199832

Adjacent sequences: A189878 A189879 A189880 * A189882 A189883 A189884

Keyword

nonn,hard

Author

Vaclav Kotesovec, Apr 29 2011

Status

approved