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 A348711 #20 Nov 11 2021 10:43:40
%S A348711 1,2,3,4,6,5,8,12,10,7,9,14,16,18,15,20,24,11,13,30,22,21,28,36,17,26,
%T A348711 32,40,19,27,42,48,25,34,60,23,33,44,38,54,35,45,56,72,50,39,52,29,46,
%U A348711 31,66,84,64,70,80,90,37,51,78,96,68,58,63,120,41,62,57,76,108,55
%N A348711 Integers sorted by decreasing value of sigma(x)/x^2, where sigma is the sum of divisors.
%C A348711 Is it possible to find distinct x and y such that sigma(x)/x^2 = sigma(y)/y^2 ?
%H A348711 Michel Marcus, <a href="/A348711/b348711.txt">Table of n, a(n) for n = 1..10000</a>
%H A348711 Michael De Vlieger, <a href="/A348711/a348711.png">Scatterplot of sigma(x)/x^2</a> for x=1..240, highlighting the position of superabundant x (in A004394) in red.
%H A348711 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a>
%e A348711 For 1,2,3,4,6,5,... sigma(x)/x^2 gives: 1 > 3/4 > 4/9 > 7/16 > 1/3 > 6/25 > ...
%t A348711 Block[{nn = Function[s, FirstPosition[s, #][[1]] &@ Fold[Max, s]]@ Array[DivisorSigma[1, #]/# &, 125], s}, s = Array[DivisorSigma[1, #]/#^2 &, nn]; #[[1 ;; FirstPosition[#, nn][[1]]]] &@ Map[FirstPosition[s, #][[1]] &, ReverseSort[s]]] (* _Michael De Vlieger_, Oct 31 2021 *)
%o A348711 (PARI) lista(nn) = Vec(vecsort(vector(10*nn, k, -sigma(k)/k^2), , 1), nn);
%Y A348711 Cf. A000203, A004394, A085790.
%K A348711 nonn
%O A348711 1,2
%A A348711 _Michel Marcus_, Oct 31 2021