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A247106
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Number of paths joining opposite corners of an n X 4 grid with every vertex appearing at most twice in the path.
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2
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5, 2100, 457712, 112269228, 28477328812, 7318410460100, 1890316186147022, 488986474759870194, 126570653719713453566, 32767699501924700122356, 8483817993681247935283336, 2196573666944370207848161336, 568727175315063817973036015946
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OFFSET
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1,1
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COMMENTS
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Limit n->infinity a(n)^(1/n) = 258.91660336499804152326399147605283475710016... . - Vaclav Kotesovec, Nov 19 2014
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LINKS
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EXAMPLE
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For n = 1 corresponds to a straight line graph with vertices {1,2,3,4}. Then the a(1) = 5 solutions are 1234, 121234, 123234, 123434, and 12123434.
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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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