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A143887
Number of ways of placing kings with no more than 4 mutual attacks on an n X n chessboard symmetric under horizontal reflection.
2
1, 2, 3, 35, 60, 2459, 2907, 447758, 410457, 237456332, 154828648, 342431110933, 169227858597, 1508376191950535, 537887672115734
OFFSET
0,2
CROSSREFS
Sequence in context: A092981 A042167 A126910 * A363499 A141503 A199696
KEYWORD
nonn,more,hard
AUTHOR
R. H. Hardin, Sep 04 2008
STATUS
approved