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 A333752 #7 Apr 04 2020 10:33:30
%S A333752 1,1,1,3,1,3,1,3,4,3,1,6,1,3,4,3,1,6,1,3,4,3,1,6,6,3,4,3,1,11,1,3,4,3,
%T A333752 6,12,1,3,4,8,1,12,1,3,9,3,1,12,8,8,4,3,1,12,6,10,4,3,1,17,1,3,11,3,6,
%U A333752 12,1,3,4,15,1,12,1,3,9,3,8,12,1,8,4,3,1,19,6,3,4,3,1,17
%N A333752 Sum of squarefree divisors of n that are <= sqrt(n).
%F A333752 G.f.: Sum_{k>=1} mu(k)^2 * k * x^(k^2) / (1 - x^k).
%t A333752 Table[DivisorSum[n, # &, # <= Sqrt[n] && SquareFreeQ[#] &], {n, 1, 90}]
%t A333752 nmax = 90; CoefficientList[Series[Sum[MoebiusMu[k]^2 k x^(k^2)/(1 - x^k), {k, 1, nmax}], {x, 0, nmax}], x] // Rest
%o A333752 (PARI) a(n) = sumdiv(n, d, if ((d^2<=n) && issquarefree(d), d)); \\ _Michel Marcus_, Apr 03 2020
%Y A333752 Cf. A005117, A048250, A066839, A069289, A069293, A097974, A333749, A333751, A333753.
%K A333752 nonn
%O A333752 1,4
%A A333752 _Ilya Gutkovskiy_, Apr 03 2020