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A143877
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Number of ways of placing kings with no more than 2 mutual attacks on an n X n chessboard symmetric under horizontal and vertical reflection.
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1
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1, 2, 1, 7, 4, 55, 17, 576, 129, 13243, 1554, 465675, 35443, 32233206, 1330673, 3746034675, 92945020
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OFFSET
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0,2
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LINKS
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CROSSREFS
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KEYWORD
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nonn,more,hard
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AUTHOR
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STATUS
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approved
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