A143877 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.

1, 2, 1, 7, 4, 55, 17, 576, 129, 13243, 1554, 465675, 35443, 32233206, 1330673, 3746034675, 92945020

Offset

0,2

Links

Table of n, a(n) for n=0..16.

Crossrefs

Sequence in context: A120872 A204771 A141512 * A319464 A019642 A339000

Adjacent sequences: A143874 A143875 A143876 * A143878 A143879 A143880

Keyword

nonn,more,hard

Author

R. H. Hardin, Sep 04 2008

Status

approved