A348130 Number of ways to place n nonattacking queens on a 2n X 2n board.

1, 4, 44, 1024, 34568, 1535440, 84871680, 5613017128, 432539436508, 38053315307904, 3763518275715424

Offset: 0

Author

Alois P. Heinz, Oct 01 2021

Keywords

• nonn
• hard
• more

Examples

			a(1) = 4:
  +-----+  +-----+  +-----+  +-----+
  | Q . |  | . . |  | . Q |  | . . |
  | . . |  | Q . |  | . . |  | . Q |
  +-----+  +-----+  +-----+  +-----+  .
		

Crossrefs

Cf. A348129.

Formula

a(n) = A348129(2n,n).

Extensions

a(9)-a(10) from Martin Ehrenstein, Oct 06 2021