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 A338535 #11 Dec 05 2020 17:53:32
%S A338535 1,6,72,120,3528,840,3600,2520,28800,10080,129600,36960,259200,50400,
%T A338535 176400,83160,352800,138600
%N A338535 a(n) is the smallest number k for which the width n at the diagonal equals the maximum width of the symmetric representation of sigma(k).
%C A338535 All numbers computed so far for this sequence have a symmetric representation of sigma that consists of a single region.
%C A338535 Additional values computed through 2000000 are a(20,21,22,24,26,30) = (277200, 1411200, 360360, 960960, 942480, 1884960).
%e A338535 a(3) = 72 = 2^3*3^2 is in the sequence since it is the smallest with maximum width 3 and width 3 at the diagonal for its symmetric representation of sigma. Number 60 is the smallest number with maximum width 3, but it has width 2 at the diagonal (see also Ax22222). a(3) has the following pattern for the widths of the legs up to the diagonal (see A249223): 1, 1, 2, 2, 2, 2, 2, 2, 3, 3, 3 for its single region.
%e A338535 a(5) = 3528 = 2^3*3^2*7^2 is in the sequence, but does not have a monotone increase of widths up to the diagonal in its single region: 1...2...3...4...3...4...3...4...5 (there are 83 legs to the diagonal).
%t A338535 (* Functions row[] and a237048[] are defined in A237048 *)
%t A338535 widthQ0[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, cW, 0]]
%t A338535 a338535[n_, b_] := Module[{list=Table[0, {b}], k, wQ}, For[k=1, k<=n, k++, wQ=widthQ0[k]; If[wQ!=0&&list[[wQ]]==0, list[[wQ]]=k]]; list]
%t A338535 Take[a338535[500000,25],18] (* sequence data *)
%Y A338535 Cf. A128605, A235791, A237048, A237591, A237593, A249223, A250071.
%K A338535 nonn,more
%O A338535 1,2
%A A338535 _Hartmut F. W. Hoft_, Nov 01 2020