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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..14.

CROSSREFS

Sequence in context: A092981 A042167 A126910 * A141503 A199696 A234423

Adjacent sequences:  A143884 A143885 A143886 * A143888 A143889 A143890

KEYWORD

nonn,more,hard

AUTHOR

R. H. Hardin, Sep 04 2008

STATUS

approved

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Last modified September 23 04:54 EDT 2020. Contains 337295 sequences. (Running on oeis4.)