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A130728
Number of ways of placing non-attacking knights on an n X n chessboard symmetric under 90-degree rotation.
0
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
CROSSREFS
Sequence in context: A130712 A276075 A321908 * A372576 A276085 A334870
KEYWORD
nonn
AUTHOR
R. H. Hardin, Aug 25 2008
STATUS
approved