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A143880 Number of ways of placing kings with no more than 2 mutual attacks on an n X n chessboard symmetric under 180 degree rotation. 1
1, 2, 3, 15, 36, 383, 1505, 28764, 197391, 6544311, 74718810 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..10.

CROSSREFS

Sequence in context: A060753 A241198 A296296 * A037388 A298370 A221860

Adjacent sequences:  A143877 A143878 A143879 * A143881 A143882 A143883

KEYWORD

nonn,more,hard

AUTHOR

R. H. Hardin, Sep 04 2008

STATUS

approved

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Last modified May 28 04:00 EDT 2020. Contains 334671 sequences. (Running on oeis4.)