A306509 - OEIS

%I #17 Aug 03 2021 12:33:48

%S 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,

%T 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,

%U 4,2,4,3,4,2,6,2,4,4,5,4,3,4,2,6,2,4,4,5,2,3,4,2

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

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

%F a(10*n) = a(n). - _Rémy Sigrist_, Feb 25 2019

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

%t Table[DivisorSigma[0,Total[IntegerDigits[n]]],{n,120}] (* _Harvey P. Dale_, Aug 03 2021 *)

%o (PARI) a(n) = numdiv(sumdigits(n)); \\ _Michel Marcus_, Feb 20 2019

%Y Cf. A000005, A007953.

%K nonn,base

%O 1,2

%A _Ctibor O. Zizka_, Feb 20 2019