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 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. 2

%I

%S 0,1,2,11,92,1097,19448,477136,14244856

%N 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.

%C This problem is slightly different from A000769 or A219760. In the first example on an 8 x 8 board, are the queens c7, d5 and e3 (or queens a2, c5 and e8) 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].

%H Vaclav Kotesovec, <a href="/A225623/a225623.pdf">Examples</a>

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

%K nonn,more,hard

%O 1,3

%A _Vaclav Kotesovec_, Aug 04 2013

%E Definition clarified by _Vaclav Kotesovec_, Dec 18 2014

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Last modified January 20 17:05 EST 2019. Contains 319335 sequences. (Running on oeis4.)