A130728 Number of ways of placing non-attacking knights on an n X n chessboard symmetric under 90-degree rotation.

1, 2, 2, 6, 3, 27, 28, 324, 338, 5991, 6875, 228512, 322056, 17782554, 30487207, 2704389848, 5451449965, 819155081866, 1981437279113, 497332226754331, 1457925225531230, 603767469974886673, 2133983730438871395

Offset

0,2

Links

Table of n, a(n) for n=0..22.

Crossrefs

Sequence in context: A130712 A276075 A321908 * A372576 A276085 A334870

Adjacent sequences: A130725 A130726 A130727 * A130729 A130730 A130731

Keyword

nonn

Author

R. H. Hardin, Aug 25 2008

Status

approved