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, 2, 3, 15, 36, 383, 1505, 28764, 197391, 6544311, 74718810

Offset

0,2

Links

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

Crossrefs

Sequence in context: A241198 A356094 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