A347980 a(n) is the smallest odd number k whose symmetric representation of sigma(k) has maximum width n.

1, 15, 315, 2145, 3465, 17325, 45045, 51975, 225225, 405405, 315315, 765765, 1576575, 2297295

Offset: 1

Author

Hartmut F. W. Hoft, Sep 22 2021

Keywords

• nonn
• more

Comments

The sequence is not increasing with the maximum width of the symmetric representation just like A347979.

Observation: a(2)..a(14) ending in 5. - Omar E. Pol, Sep 23 2021

Examples

			The pattern of maximum widths of the parts in the symmetric representation of sigma for the first four terms in the sequence is:
   a(n) parts  successive widths
     1:   1          1
    15:   3        1 2 1
   315:   3        1 3 1
  2145:   7    1 2 3 4 3 2 1
		

Crossrefs

Cf. A174973, A237048, A237270, A237271, A237591, A237593, A238443, A249351 (widths), A250070, A262045, A341969, A341970, A341971, A347979.

Programs

Mathematica

a262045[n_] := Module[{a=Accumulate[Map[If[Mod[n - # (#+1)/2, #]==0, (-1)^(#+1), 0] &, Range[Floor[(Sqrt[8n+1]-1)/2]]]]}, Join[a, Reverse[a]]]
a347980[n_, mw_] := Module[{list=Table[0, mw], i, v}, For[i=1, i<=n, i+=2, v=Max[a262045[i]]; If [list[[v]]==0, list[[v]]=i]]; list]
a347980[2500000,14] (* long evaluation time *)