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A143891 Number of ways of placing kings with no more than 4 mutual attacks on an n X n chessboard symmetric about the diagonal and under 90 degree rotation. 0
1, 2, 1, 5, 2, 15, 7, 68, 23, 370, 104, 2649, 571, 25209, 4176, 313503, 39827, 5212881, 500254, 114569731, 8348616 (list; graph; refs; listen; history; internal format)
OFFSET

0,2

CROSSREFS

Sequence in context: A097131 A192263 A109738 * A030400 A115345 A194092

Adjacent sequences:  A143888 A143889 A143890 * A143892 A143893 A143894

KEYWORD

nonn

AUTHOR

R. H. Hardin (rhhardin(AT)att.net), Sep 04 2008

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Last modified February 15 05:45 EST 2012. Contains 205694 sequences.