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A162964
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a(n) = sigma(sigma(sigma(sigma(sigma(n))))).
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1
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1, 15, 24, 60, 120, 360, 168, 480, 168, 360, 360, 1170, 480, 1512, 1512, 210, 360, 1170, 728, 1680, 576, 480, 1512, 4800, 210, 1680, 1344, 3276, 992, 2016, 576, 1651, 1560, 3276, 1560, 1512, 1512, 4800, 3276, 4064, 1680, 5952, 1560, 5040, 4800, 2016, 1560, 5040
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OFFSET
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1,2
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LINKS
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FORMULA
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MAPLE
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with(numtheory); f:=n->sigma(sigma(sigma(sigma(sigma(n))))); [seq(f(n), n=1..100)];
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MATHEMATICA
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Table[Nest[DivisorSigma[1, #]&, n, 5], {n, 50}] (* Harvey P. Dale, Apr 19 2013 *)
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PROG
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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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