A189877 Number of ways to place n nonattacking composite pieces queen + rider[2,4] on an n X n chessboard.

1, 0, 0, 2, 0, 0, 0, 0, 0, 4, 56, 172, 680, 1348, 6576, 34568, 107624, 413760, 1697288, 8035558, 37441416, 192483420, 1115143224

Offset: 1

Author

Vaclav Kotesovec, Apr 29 2011

Keywords

• nonn
• hard

Comments

a(n) is also number of permutations p of 1,2,...,n satisfying |p(i+2k)-p(i)|<>4k AND |p(j+4k)-p(j)|<>2k AND |p(m+k)-p(m)|<>k for all i>=1, j>=1, m>=1, k>=1, i+2k<=n, j+4k<=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, A189874, A189876, A189855