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A110757 a(n) = number of divisors of N, where N = reverse concatenation of 1,2,3,...,n. 4
1, 4, 4, 4, 8, 4, 4, 12, 18, 8, 4, 8, 8, 16, 48, 16, 96, 576, 16, 32, 16, 32, 16, 32, 64, 256, 96, 32, 128, 256, 8, 64, 32, 128, 384, 144, 16, 8, 64, 32, 256, 64, 8, 192, 96, 32, 128, 128, 8, 64, 8, 128, 1280, 2560, 8, 24, 16, 64, 8, 8, 32, 384, 48, 64, 128, 128 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..66.

FORMULA

a(n) = A000005(A000422(n)). - Jinyuan Wang, May 23 2020

EXAMPLE

a(3) = tau(321) = 4.

MATHEMATICA

s = ""; Do[s = ToString[n] <> s; Print[DivisorSigma[0, ToExpression[s]]], {n, 1, 45}] (* Ryan Propper, Sep 23 2005 *)

Table[DivisorSigma[0, FromDigits[Flatten[IntegerDigits/@Range[n, 1, -1]]]], {n, 50}] (* The program takes a long time to run. *) (* Harvey P. Dale, Jun 06 2018 *)

CROSSREFS

Cf. A000005, A000422, A110756, A110758, A110759, A110760.

Sequence in context: A342484 A105352 A132200 * A167184 A276113 A232406

Adjacent sequences:  A110754 A110755 A110756 * A110758 A110759 A110760

KEYWORD

nonn,base

AUTHOR

Amarnath Murthy, Aug 11 2005

EXTENSIONS

More terms from Ryan Propper, Sep 23 2005

a(46)-a(66) from Jinyuan Wang, May 23 2020

STATUS

approved

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Last modified September 23 07:00 EDT 2021. Contains 347609 sequences. (Running on oeis4.)