A348130 - OEIS

%I #15 Oct 07 2021 00:19:18

%S 1,4,44,1024,34568,1535440,84871680,5613017128,432539436508,

%T 38053315307904,3763518275715424

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

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

%e a(1) = 4:

%e   +-----+  +-----+  +-----+  +-----+

%e   | Q . |  | . . |  | . Q |  | . . |

%e   | . . |  | Q . |  | . . |  | . Q |

%e   +-----+  +-----+  +-----+  +-----+  .

%Y Cf. A348129.

%K nonn,hard,more

%O 0,2

%A _Alois P. Heinz_, Oct 01 2021

%E a(9)-a(10) from _Martin Ehrenstein_, Oct 06 2021