A110757 a(n) = number of divisors of N, where N = reverse concatenation of 1,2,3,...,n.

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

Offset: 1

Author

Amarnath Murthy, Aug 11 2005

Keywords

• nonn
• base

Examples

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

Links

• Tyler Busby, Table of n, a(n) for n = 1..109

Crossrefs

Cf. A000005, A000422, A176024.

Cf. A110756, A110758, A110759, A110760.

Programs

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 *)

Formula

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

Extensions

More terms from Ryan Propper, Sep 23 2005

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