OFFSET
1,2
FORMULA
a(10*n) = a(n). - Rémy Sigrist, Feb 25 2019
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
KEYWORD
nonn,base
AUTHOR
Ctibor O. Zizka, Feb 20 2019
STATUS
approved