A122667 a(n) = d(n)_d(n) = A122618(d(n)), where d = A000005, and A122618 = "n read in base n".

1, 2, 2, 3, 2, 4, 2, 4, 3, 4, 2, 6, 2, 4, 4, 5, 2, 6, 2, 6, 4, 4, 2, 8, 3, 4, 4, 6, 2, 8, 2, 6, 4, 4, 4, 9, 2, 4, 4, 8, 2, 8, 2, 6, 6, 4, 2, 10, 3, 6, 4, 6, 2, 8, 4, 8, 4, 4, 2, 14, 2, 4, 6, 7, 4, 8, 2, 6, 4, 8, 2, 14, 2, 4, 6, 6, 4, 8, 2, 10, 5, 4, 2, 14, 4, 4, 4, 8, 2, 14, 4, 6, 4, 4, 4, 14, 2, 6, 6, 9

Offset: 1

Author

N. J. A. Sloane, Sep 22 2006

Keywords

• nonn
• base

Comments

See A122618 for notation.

Only terms >= 12 are different from d(n), the first one is a(60). - M. F. Hasler, Apr 22 2015

Links

• Antti Karttunen, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000005, A122668.

Programs

Mathematica

a[n_]:=FromDigits[IntegerDigits[tau=DivisorSigma[0,n]], tau]; Array[a, 100] (* Stefano Spezia, May 03 2025 *)

PARI

A122667(n)=A122618(numdiv(n)) \\ M. F. Hasler, Apr 22 2015