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A385494 Total number of 1's in the decimal digits of the divisors of n.

%I A385494 #33 Aug 29 2025 10:16:35
%S A385494 1,1,1,1,1,1,1,1,1,2,3,2,2,2,2,2,2,2,2,2,2,3,1,2,1,2,1,2,1,3,2,2,3,2,
%T A385494 1,3,1,2,2,2,2,3,1,3,2,1,1,3,1,2,3,2,1,2,3,2,2,1,1,4,2,2,2,2,2,3,1,2,
%U A385494 1,3,2,3,1,1,2,2,3,2,1,3,2,2,1,4,2,1,1,3,1,4,3,1,2,1,2,3,1,2,3,3
%N A385494 Total number of 1's in the decimal digits of the divisors of n.
%H A385494 Robert Israel, <a href="/A385494/b385494.txt">Table of n, a(n) for n = 1..10000</a>
%e A385494 a(11) = 3 because of the divisors of 11, there is one 1 in 1 and two in 11.
%e A385494 a(60) = 4 because of the divisors of 60, there is one 1 in 1, one in 10, one in 12, one in 15 and none in the other divisors.
%p A385494 f:= proc(n) local d; add(numboccur(1, convert(d,base,10)),d=numtheory:-divisors(n)) end proc:
%p A385494 map(f, [$1..100]);
%t A385494 a[n_]:=Count[IntegerDigits[Divisors[n]]//Flatten,1]; Array[a,100] (* _Stefano Spezia_, Aug 28 2025 *)
%o A385494 (Python)
%o A385494 from sympy import divisors
%o A385494 def a(n): return sum(str(d).count("1") for d in divisors(n, generator=True))
%o A385494 print([a(n) for n in range(1, 101)]) # _Michael S. Branicky_, Aug 27 2025
%o A385494 (PARI) a(n) = sumdiv(n, d, #select(x->(x==1), digits(d))); \\ _Michel Marcus_, Aug 28 2025
%Y A385494 Cf. A093653, A387357.
%K A385494 nonn,base,new
%O A385494 1,10
%A A385494 _Robert Israel_, Aug 27 2025