A143871 Number of ways of placing kings with no more than 1 mutual attack on an n X n chessboard symmetric under horizontal reflection.

1, 2, 3, 13, 18, 425, 371, 27872, 25147, 8144945, 4679546, 6097351181, 3118820527, 16876586891126, 6022295415137

Offset

0,2

Links

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

Crossrefs

Sequence in context: A215386 A352539 A338216 * A225517 A254462 A275030

Adjacent sequences: A143868 A143869 A143870 * A143872 A143873 A143874

Keyword

nonn,more,hard

Author

R. H. Hardin, Sep 04 2008

Status

approved