A189858 Number of ways to place n nonattacking composite pieces rook + rider[3,4] on an n X n chessboard.

1, 2, 6, 24, 80, 326, 1566, 9544, 53696, 347382, 2566892, 21907934, 184868860, 1704360992, 17294597926, 192725663600, 2139133978996

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+3k)-p(i)|<>4k AND |p(j+4k)-p(j)|<>3k for all i>=1, j>=1, k>=1, i+3k<=n, j+4k<=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. A000170, A189851, A189855.