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%I #29 Jan 09 2022 09:38:11
%S 0,1,2,11,92,1097,19448,477136,14244856,537809179,24194010708,
%T 1317062528249
%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, 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].
%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
%E a(10)-a(12) from _Martin Ehrenstein_, Jan 09 2022
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