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Number of ways of placing kings with no more than 3 mutual attacks on an n X n chessboard symmetric under 180 degree rotation.
1

%I #5 Oct 20 2014 18:34:37

%S 1,2,3,15,52,383,2273,28764,295391,6544311,116636234

%N Number of ways of placing kings with no more than 3 mutual attacks on an n X n chessboard symmetric under 180 degree rotation.

%K nonn,more,hard

%O 0,2

%A _R. H. Hardin_, Sep 04 2008