A189876 Number of ways to place n nonattacking composite pieces queen + rider[2,3] on an n X n chessboard.

1, 0, 0, 2, 10, 0, 0, 0, 0, 16, 60, 40, 304, 620, 2512, 8734, 28410, 94312, 345824, 1391072, 5759566, 25227796, 121663032, 635977968

Offset: 1

Author

Vaclav Kotesovec, Apr 29 2011

Keywords

• nonn
• hard

Comments

(in fairy chess the rider [2,3] is called a Zebrarider)

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

Links

• 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, A189873, A189854