A189870 Number of ways to place n nonattacking composite pieces queen + leaper[3,4] on an n X n chessboard.

1, 0, 0, 2, 2, 4, 28, 0, 20, 52, 280, 1192, 5520, 20196, 115936, 701836, 4174032, 27261284, 193428616, 1445733328, 11133210948

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+3)-p(i)|<>4 AND |p(j+4)-p(j)|<>3 AND |p(m+k)-p(m)|<>k for all i>=1, j>=1, m>=1, k>=1, i+3<=n, j+4<=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. A051223, A189865, A189868, A189568