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A145238
1/3 of the number of 3-colorings of an n X n array symmetric about both diagonal and antidiagonal.
0
1, 2, 8, 24, 144, 648, 5904, 40392, 561744, 5871528, 124982208, 2000735640, 65289654720, 1603001126808, 80277953271984, 3025716988718520, 232703590361105952, 13472417658155610888, 1592017750060187494896
OFFSET
1,2
CROSSREFS
Sequence in context: A361991 A087982 A176475 * A093458 A242456 A353779
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 05 2008
STATUS
approved