A225623 Number of ways to arrange 2n queens on an n X n chessboard, with no more than 2 queens in each row, column or diagonal.

0, 1, 2, 11, 92, 1097, 19448, 477136, 14244856, 537809179, 24194010708, 1317062528249

Offset: 1

Author

Vaclav Kotesovec, Aug 04 2013

Keywords

• nonn
• more
• hard

Comments

This problem is slightly different from A000769 or A219760. In the first example on an 8 x 8 board, the queens c7, d5 and e3 (or queens a2, c5 and e8) are in a line, but such case is allowed. The elementary step can be only [0,1], [1,0] or [1,1], not for example [1,2] or [2,3].

Links

• Vaclav Kotesovec, Examples

Crossrefs

Cf. A000170, A000769, A001499, A001501, A058528, A075754, A172544, A172541.

Extensions

Definition clarified by Vaclav Kotesovec, Dec 18 2014

a(10)-a(12) from Martin Ehrenstein, Jan 09 2022