%I

%S 1,2,5,17,92,581,4989,54250,776877,14503255,356467268,11553201879,

%T 495106836021

%N Number of ways of placing kings with no more than 2 mutual attacks on an n X n chessboard symmetric about main diagonal.

%K nonn,more,hard

%O 0,2

%A _R. H. Hardin_, Sep 04 2008