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 A160241 Number of Greek Key Tours on a 7 X n grid. 1
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS 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 LINKS N. Johnston, On Maximal Self-Avoiding Walks. CROSSREFS Cf. A046994, A046995, A145156, A145157. Sequence in context: A212856 A169608 A184754 * A020998 A012504 A012689 Adjacent sequences:  A160238 A160239 A160240 * A160242 A160243 A160244 KEYWORD nonn AUTHOR Nathaniel Johnston, May 05 2009 EXTENSIONS a(11)-a(30) from Andrew Howroyd, Nov 07 2015 STATUS approved

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Last modified January 18 16:40 EST 2019. Contains 319271 sequences. (Running on oeis4.)