A306509 a(n) is the number of divisors of the sum of digits of n.

1, 2, 2, 3, 2, 4, 2, 4, 3, 1, 2, 2, 3, 2, 4, 2, 4, 3, 4, 2, 2, 3, 2, 4, 2, 4, 3, 4, 2, 2, 3, 2, 4, 2, 4, 3, 4, 2, 6, 3, 2, 4, 2, 4, 3, 4, 2, 6, 2, 2, 4, 2, 4, 3, 4, 2, 6, 2, 4, 4, 2, 4, 3, 4, 2, 6, 2, 4, 4, 2, 4, 3, 4, 2, 6, 2, 4, 4, 5, 4, 3, 4, 2, 6, 2, 4, 4, 5, 2, 3, 4, 2

Offset

1,2

Links

Table of n, a(n) for n=1..92.

Formula

a(n) = A000005(A007953(n)).

a(10*n) = a(n). - Rémy Sigrist, Feb 25 2019

Example

a(17) = A000005(A007953(17)) = A000005(8) = 4.

Mathematica

Table[DivisorSigma[0, Total[IntegerDigits[n]]], {n, 120}] (* Harvey P. Dale, Aug 03 2021 *)

Prog

(PARI) a(n) = numdiv(sumdigits(n)); \\ Michel Marcus, Feb 20 2019

Crossrefs

Cf. A000005, A007953.

Sequence in context: A327536 A341946 A339915 * A083867 A076888 A357171

Adjacent sequences: A306506 A306507 A306508 * A306510 A306511 A306512

Keyword

nonn,base

Author

Ctibor O. Zizka, Feb 20 2019

Status

approved