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A143873
Number of ways of placing kings with no more than 1 mutual attack on an n X n chessboard symmetric about both diagonal and antidiagonal.
1
1, 2, 3, 5, 8, 21, 53, 158, 503, 2181, 9658, 53517, 313683, 2389270
OFFSET
0,2
CROSSREFS
Sequence in context: A041457 A161468 A229040 * A273046 A117774 A053056
KEYWORD
nonn,more,hard
AUTHOR
R. H. Hardin, Sep 04 2008
STATUS
approved