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A160240
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Number of Greek-Key Tours on a 6 X n grid.
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1
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1, 6, 78, 469, 3501, 22144, 144476, 899432, 5585508, 34092855, 206571444, 1241016042, 7407467656, 43975776229, 259779839242, 1528563721468, 8960651209082, 52368047294410, 305173796833144, 1774059940879290, 10289839706255591, 59564855651625602, 344177608427972004, 1985502681113986836, 11437008315770485918, 65791536638478271291, 377999748832914166324, 2169320756101096085597, 12436728915873118081588, 71232070407411735554025
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OFFSET
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1,2
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COMMENTS
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Greek Key Tours are self-avoiding walks that touch every vertex of the grid and start at the bottom-left corner.
The sequence may be enumerated using standard methods for counting Hamiltonian cycles on a modified graph with two additional nodes, one joined to a corner vertex and the other joined to all other vertices. - Andrew Howroyd, Nov 07 2015
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LINKS
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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