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 A256440 #15 Dec 22 2017 08:46:13
%S A256440 1,1,2,1,3,2,1,3,2,4,1,5,3,2,4,1,5,3,2,4,6,1,7,5,3,2,4,6,1,7,5,3,2,4,
%T A256440 8,6,1,7,5,3,9,2,4,8,6,1,7,5,3,9,2,4,10,8,6,1,11,7,5,3,9,2,4,10,8,6,1,
%U A256440 11,7,5,3,9,2,4,10,8,6,12,1,13,11,7,5,3,9,2,4,10,8,6,12
%N A256440 Regular triangle where the n-th row lists the integers k between 1 and n ordered by increasing value of sigma(k)/k where sigma is the sum of divisors, A000203.
%H A256440 Michel Marcus, <a href="/A256440/b256440.txt">Rows n = 1..100 of triangle, flattened</a>
%H A256440 Michel Marcus, <a href="/A256440/a256440.txt">100 rows</a>
%e A256440 Triangle starts:
%e A256440 1;
%e A256440 1, 2;
%e A256440 1, 3, 2;
%e A256440 1, 3, 2, 4;
%e A256440 1, 5, 3, 2, 4;
%e A256440 1, 5, 3, 2, 4, 6;
%e A256440 1, 7, 5, 3, 2, 4, 6;
%e A256440 ...
%t A256440 f[n_] := Block[{t = Table[0, {n}], j, k}, For[j = 1, j <= n, j++, t[[j]] = {}; For[k = 1, k <= j, k++, AppendTo[t[[j]], DivisorSigma[1, k]/k]]]; Ordering /@ t]; f@ 13 // Flatten (* _Michael De Vlieger_, Mar 29 2015 *)
%o A256440 (PARI) lista(nn) = {for (n=1, nn, v = vector(n, k, sigma(k)/k); w = vecsort(v,,1); for (k=1, n, print1(w[k], ", ")); print(););}
%Y A256440 Cf. A000203, A247015, A247022.
%K A256440 nonn,tabl
%O A256440 1,3
%A A256440 _Michel Marcus_, Mar 29 2015