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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

Table of n, a(n) for n=1..30.

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

Cf. A110751, A110752.

Sequence in context: A262000 A007276 A052619 * A154670 A041626 A039608

Adjacent sequences:  A110750 A110751 A110752 * A110754 A110755 A110756

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 August 4 03:57 EDT 2021. Contains 346442 sequences. (Running on oeis4.)