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A110753
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a(n) is the number of divisors of the concatenation of 2178 with itself n times.
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3
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18, 72, 384, 288, 576, 3072, 1152, 9216, 7680, 9216, 6144, 24576, 2304, 18432, 3145728, 147456, 4608, 491520, 288, 147456, 9437184, 98304, 4608, 12582912, 589824, 36864, 1179648, 589824, 36864, 201326592
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OFFSET
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1,1
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COMMENTS
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2178 has the property that any number of concatenations of it with itself and its digit reversal have the same set of distinct prime factors.
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LINKS
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EXAMPLE
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a(2) = tau(21782178) = 72.
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MATHEMATICA
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k = 0; Do[k = (10^4 * k) + 2178; Print[DivisorSigma[0, k]], {n, 1, 30}] (* Ryan Propper, Aug 28 2005 *)
Table[DivisorSigma[0, FromDigits[PadRight[{}, 4n, {2, 1, 7, 8}]]], {n, 30}] (* Harvey P. Dale, Jun 23 2014 *)
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CROSSREFS
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KEYWORD
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base,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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