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A143892 Number of ways of placing kings with no more than 4 mutual attacks on an n X n chessboard symmetric under 90-degree rotation. 1
1, 2, 1, 5, 6, 29, 47, 300, 665, 5276, 15554, 160307, 632041, 8448701, 44021226 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

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

EXAMPLE

Example: for n=3 the a(3)=5 solutions are

. . .   . . .   K . K   K . K   . K .

. . .   . K .   . . .   . K .   K . K

. . .   . . .   K . K   K . K   . K .

CROSSREFS

Cf. A143870, A143875, A143881, A143886.

Cf. A143886, A143887, A143888, A143889, A143890, A143891, A143893.

Sequence in context: A095242 A125080 A217105 * A129321 A064642 A193630

Adjacent sequences:  A143889 A143890 A143891 * A143893 A143894 A143895

KEYWORD

nonn,more,hard

AUTHOR

R. H. Hardin, Sep 04 2008

STATUS

approved

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Last modified November 17 08:39 EST 2019. Contains 329217 sequences. (Running on oeis4.)