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A328341
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Number of geometrically distinct open knight's tours on a 4 X n chessboard.
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3
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0, 0, 3, 0, 22, 186, 1603, 7772, 47478, 303278, 1671273, 9121582, 50322028, 270896326, 1426536267, 7454807822, 38607660199, 197696949844, 1003736587788, 5060326202622, 25334034892953, 126024078250318, 623383415637750, 3067618264121349, 15022847233751804, 73245459228339114
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OFFSET
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1,3
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LINKS
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FORMULA
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EXAMPLE
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a(3) = 3 because there are two symmetric and one asymmetric tour:
+----+----+----+----+ +----+----+----+----+ +----+----+----+----+
| 8 | 11 | 6 | 3 | | 1 | 4 | 7 | 10 | | 1 | 4 | 7 | 10 |
+----+----+----+----+ +----+----+----+----+ +----+----+----+----+
| 1 | 4 | 9 | 12 | | 8 | 11 | 2 | 5 | | 12 | 9 | 2 | 5 |
+----+----+----+----+ +----+----+----+----+ +----+----+----+----+
| 10 | 7 | 2 | 5 | | 3 | 6 | 9 | 12 | | 3 | 6 | 11 | 8 |
+----+----+----+----+ +----+----+----+----+ +----+----+----+----+
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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