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 A326039 #10 Jul 29 2019 10:27:59
%S A326039 1,1,4,1,1,4,4,1,1,9,4,4,1,4,4,1,9,1,4,1,16,36,4,4,1,1,4,4,1,36,16,9,
%T A326039 16,9,16,1,1,4,4,9,1,16,4,4,1,36,16,4,1,1,36,49,9,4,36,4,16,9,4,4,1,
%U A326039 16,4,1,4,144,4,9,16,144,36,1,1,1,4,4,16,4,16,1,121,9,4,16,36,4,4,36,9,9,16,4,64,144,4,36
%N A326039 Largest square dividing the sum of divisors of n: a(n) = A008833(sigma(n)).
%H A326039 Antti Karttunen, <a href="/A326039/b326039.txt">Table of n, a(n) for n = 1..20000</a>
%H A326039 <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>
%F A326039 a(n) = A008833(A000203(n)) = A326038(n)^2.
%F A326039 a(n) = A000203(n) - A326040(n).
%t A326039 Module[{sqs=Range[100,1,-1]^2},Table[SelectFirst[sqs,Divisible[ DivisorSigma[ 1,n],#]&],{n,100}]] (* _Harvey P. Dale_, Jul 29 2019 *)
%o A326039 (PARI)
%o A326039 A008833(n) = (n/core(n));
%o A326039 A326039(n) = A008833(sigma(n));
%Y A326039 Cf. A000203, A008833, A326038, A326040.
%K A326039 nonn
%O A326039 1,3
%A A326039 _Antti Karttunen_, Jun 05 2019