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 A338538 #13 Dec 05 2020 17:54:44
%S A338538 882,990,7938,2100,22050,13200,63504,12600,304200,32760,88200,102960
%N A338538 a(n) is the smallest number k for which the width n at the diagonal is two smaller than the maximum width of the symmetric representation of sigma(k), the sum of divisors of k.
%C A338538 All numbers computed so far for this sequence have a symmetric representation of sigma that consists of a single region; see A237270 and A237593.
%C A338538 Additional values computed through 2000000 are a(14,15,16,17,18,20,22,24,28) = (171360, 1960200, 240240, 705600, 327600, 957600, 1375920, 1108800, 1663200).
%e A338538 a(1) = 882 = 2*3^2*7^2 is in the sequence since it is the smallest with maximum width 3 and width 1 at the diagonal. The widths of its 41 legs to the diagonal are: 1..2..1..2..3..2..3..2..1.
%t A338538 (* Functions row[] and a237048[] are defined in A237048 *)
%t A338538 widthQ2[n_] := Module[{r=row[n], cW=0, mW=0, k}, For[k=1, k<=r, k++, cW+=(-1)^(k+1) a237048[n, k]; If[cW>mW, mW=cW]]; If[mW==cW+2 && cW>0, cW, 0]]
%t A338538 a338538[n_, b_] := Module[{list=Table[0, {b}], k, wQ}, For[k=1, k<=n, k++, wQ=widthQ2[k]; If[wQ!=0&&list[[wQ]]==0, list[[wQ]]=k]]; list]
%t A338538 Take[a338538[1000000,20],12] (* sequence data *)
%Y A338538 Cf. A235791, A237048, A237270, A237591, A237593, A249223, A338535, A338536.
%K A338538 nonn,more
%O A338538 1,1
%A A338538 _Hartmut F. W. Hoft_, Nov 01 2020