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A077189
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Smallest concatenation 123...(k-1) k (k-1)...321 (a concatenation of natural numbers from 1 to k and back to 1) that is a multiple of 2n-1, or 0 if no such number exists.
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3
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OFFSET
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1,2
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COMMENTS
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a(5k+3) = 0. Are there any other values of n such that a(n) = 0?
The next value, 2n-1 = 17, has k = 109, for a total of 435 digits and is too large to include. - Franklin T. Adams-Watters, Jun 02 2006
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LINKS
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EXAMPLE
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a(5) = 12321 is a multiple of 9.
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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