A143878 Number of ways of placing kings with no more than 2 mutual attacks on an n X n chessboard symmetric about main diagonal.

1, 2, 5, 17, 92, 581, 4989, 54250, 776877, 14503255, 356467268, 11553201879, 495106836021

Offset

0,2

Links

Table of n, a(n) for n=0..12.

Crossrefs

Sequence in context: A026822 A059248 A203006 * A081546 A103511 A254132

Adjacent sequences: A143875 A143876 A143877 * A143879 A143880 A143881

Keyword

nonn,more,hard

Author

R. H. Hardin, Sep 04 2008

Status

approved