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A160241
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Number of Greek Key Tours on a 7 X n grid.
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1
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1, 7, 164, 1337, 16262, 144476, 1510446, 13506023, 132712481, 1185979605, 11264671456, 100572103736, 935551716239, 8347069749600, 76604373779441, 683160282998544, 6213169249692192, 55392188422262591, 500676083630457127, 4462726297606450762, 40165465812088131228, 357958181000067374304, 3212099862174948821718, 28623565473267451344466, 256312533945178149983147, 2283878397650977479239903, 20420964710002966369773032, 181952098315164452547737813, 1625193628709305194920610168, 14480051230931926406392771755
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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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