A189856 Number of ways to place n nonattacking composite pieces rook + rider[2,5] on an n X n chessboard.

1, 2, 6, 24, 120, 392, 1810, 10400, 72228, 589674, 3823906, 29420944, 266232984, 2711139976, 30669073348, 316482938974

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)|<>5k AND |p(j+5k)-p(j)|<>2k for all i>=1, j>=1, k>=1, i+2k<=n, j+5k<=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, A189854, A189855