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A143892
Number of ways of placing kings with no more than 4 mutual attacks on an n X n chessboard symmetric under 90-degree rotation.
1
1, 2, 1, 5, 6, 29, 47, 300, 665, 5276, 15554, 160307, 632041, 8448701, 44021226
OFFSET
0,2
EXAMPLE
Example: for n=3 the a(3)=5 solutions are
. . . . . . K . K K . K . K .
. . . . K . . . . . K . K . K
. . . . . . K . K K . K . K .
KEYWORD
nonn,more,hard
AUTHOR
R. H. Hardin, Sep 04 2008
STATUS
approved