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A131180
Number of ways of placing non-attacking knights on an n X n chessboard symmetric under 180 degree rotation.
0
1, 2, 4, 14, 53, 313, 2170, 31896, 387802, 11507269, 290487893, 15905409672, 816544187208, 90196956861272, 9093799327168995, 2023727669041604444
OFFSET
0,2
CROSSREFS
Sequence in context: A006385 A322859 A183949 * A047990 A000939 A367558
KEYWORD
nonn
AUTHOR
R. H. Hardin, Aug 25 2008
STATUS
approved