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A110753 a(n) is the number of divisors of the concatenation of 2178 with itself n times. 3
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
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.
LINKS
EXAMPLE
a(2) = tau(21782178) = 72.
MATHEMATICA
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 *)
CROSSREFS
Sequence in context: A262000 A007276 A052619 * A154670 A041626 A039608
KEYWORD
base,nonn
AUTHOR
Amarnath Murthy, Aug 11 2005
EXTENSIONS
More terms from Ryan Propper, Aug 28 2005
STATUS
approved

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Last modified March 18 22:47 EDT 2024. Contains 370951 sequences. (Running on oeis4.)