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A059460
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Iteration of unitary-sigma function: a(1) = 2, a(n) = usigma(a(n-1)).
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1
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2, 3, 4, 5, 6, 12, 20, 30, 72, 90, 180, 300, 520, 756, 1120, 1584, 2040, 3888, 4148, 5580, 9600, 13416, 22176, 31680, 46800, 61880, 108864, 126880, 171864, 276480, 344232, 492480, 639600, 1039584, 1663200, 2306304, 3454080, 6390144
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OFFSET
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1,1
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LINKS
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MATHEMATICA
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f[n_] := Times @@ (1 + Power@@@ FactorInteger[n]); NestList[f, 2, 30] (* Amiram Eldar, Aug 11 2019 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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