A143887 Number of ways of placing kings with no more than 4 mutual attacks on an n X n chessboard symmetric under horizontal reflection.

1, 2, 3, 35, 60, 2459, 2907, 447758, 410457, 237456332, 154828648, 342431110933, 169227858597, 1508376191950535, 537887672115734

Offset

0,2

Links

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

Crossrefs

Sequence in context: A092981 A042167 A126910 * A363499 A141503 A199696

Adjacent sequences: A143884 A143885 A143886 * A143888 A143889 A143890

Keyword

nonn,more,hard

Author

R. H. Hardin, Sep 04 2008

Status

approved