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%I #5 Jan 17 2022 19:55:28
%S 0,140,317544,54472800228
%N Number of solutions to the Xqueens problem on a 2n X 2n board that are both sparse and paired.
%H Don Knuth, <a href="http://cs.stanford.edu/~knuth/papers/Xqueens-and-Xqueenons.pdf">Xqueens and Xqueenons</a>, 2021.
%Y Cf. A350611-A350613.
%K nonn,more
%O 1,2
%A _Don Knuth_, Jan 16 2022