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A143876
Number of ways of placing kings with no more than 2 mutual attacks on an n X n chessboard symmetric under horizontal reflection.
1
1, 2, 3, 27, 26, 1119, 921, 122658, 74887, 43743593, 18775998, 43803694319, 14699916393, 143879089856822, 34113001129873
OFFSET
0,2
CROSSREFS
Sequence in context: A258766 A056722 A181225 * A184506 A126203 A126655
KEYWORD
nonn,more,hard
AUTHOR
R. H. Hardin, Sep 04 2008
STATUS
approved