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A347980
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a(n) is the smallest odd number k whose symmetric representation of sigma(k) has maximum width n.
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5
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1, 15, 315, 2145, 3465, 17325, 45045, 51975, 225225, 405405, 315315, 765765, 1576575, 2297295
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OFFSET
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1,2
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COMMENTS
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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
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LINKS
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EXAMPLE
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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
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MATHEMATICA
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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 *)
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CROSSREFS
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Cf. A174973, A237048, A237270, A237271, A237591, A237593, A238443, A249351 (widths), A250070, A262045, A341969, A341970, A341971, A347979.
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KEYWORD
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nonn,more
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AUTHOR
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STATUS
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approved
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