This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A083899 #8 Jan 04 2024 01:48:37
%S A083899 1,2,2,3,1,3,1,3,2,3,2,5,2,3,2,3,1,3,1,5,3,4,2,6,1,3,2,4,1,5,2,4,4,3,
%T A083899 1,5,1,2,3,6,2,6,2,6,2,3,1,6,1,3,2,4,1,3,2,4,2,2,1,8,1,3,3,4,2,6,1,4,
%U A083899 3,4,1,6,1,2,2,3,2,4,1,6,2,3,1,8,1,3,2,6,1,5,2,4,3,2,1,7,1,3,4,6,2,5,2,5,3
%N A083899 Number of divisors of n with largest digit <= 4 (base 10).
%F A083899 a(n) = A083898(n) + A083891(n) = A083900(n) - A083892(n).
%F A083899 Asymptotic mean: Limit_{m->oo} (1/m) * Sum_{k=1..m} a(k) = Sum_{k>=1} 1/A007091(k) = 3.92521682598923397031... . - _Amiram Eldar_, Jan 04 2024
%t A083899 a[n_] := DivisorSum[n, 1 &, Max[IntegerDigits[#]] <= 4 &]; Array[a, 100] (* _Amiram Eldar_, Jan 04 2024 *)
%Y A083899 Cf. A054055, A000005, A007091, A083891, A083892, A083898, A083900.
%K A083899 nonn,base
%O A083899 1,2
%A A083899 _Reinhard Zumkeller_, May 08 2003