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A143880
Number of ways of placing kings with no more than 2 mutual attacks on an n X n chessboard symmetric under 180 degree rotation.
1
1, 2, 3, 15, 36, 383, 1505, 28764, 197391, 6544311, 74718810
OFFSET
0,2
CROSSREFS
Sequence in context: A241198 A356094 A296296 * A037388 A298370 A221860
KEYWORD
nonn,more,hard
AUTHOR
R. H. Hardin, Sep 04 2008
STATUS
approved