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A145157
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Number of Greek-key tours on an n X n board; i.e., self-avoiding walks on n X n grid starting in top left corner.
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7
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1, 2, 8, 52, 824, 22144, 1510446, 180160012, 54986690944, 29805993260994, 41433610713353366, 103271401574007978038, 660340630211753942588170, 7618229614763015717175450784, 225419381425094248494363948728158
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OFFSET
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1,2
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COMMENTS
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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 08 2015
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LINKS
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Table of n, a(n) for n=1..15.
N. Johnston, On Maximal Self-Avoiding Walks
Ville H. Pettersson, Enumerating Hamiltonian Cycles, The Electronic Journal of Combinatorics, Volume 21, Issue 4, 2014.
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CROSSREFS
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Cf. A046994, A046995, A145156, A160240, A160241.
Cf. A000532, A001184, A120443, A003763, A271507, A007764.
Sequence in context: A057629 A191507 A191602 * A323871 A183945 A193651
Adjacent sequences: A145154 A145155 A145156 * A145158 A145159 A145160
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KEYWORD
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hard,nonn,walk
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AUTHOR
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Nathaniel Johnston, Oct 03 2008
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EXTENSIONS
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a(9)-a(15) from Andrew Howroyd, Nov 08 2015
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STATUS
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approved
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