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A067065
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Numbers n such that sigma(sigma(sigma(n))) == 6*sigma(n).
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1
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20, 26, 41, 44, 65, 83, 132, 133, 140, 182, 188, 195, 249, 287, 299, 420, 546, 564, 620, 644, 764, 806, 861, 897, 1001, 1115, 1169, 1271, 28644, 32172, 35052, 39116, 40796, 41478, 42315, 47492, 50162, 51513, 52143, 53745, 54033, 54483, 56427, 56642
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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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Select[Range[60000], Nest[DivisorSigma[1, #]&, #, 3]==6*DivisorSigma[1, #]&] (* Harvey P. Dale, Oct 04 2016 *)
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PROG
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(PARI) { n=0; for (m=1, 10^10, if (sigma(sigma(sigma(m))) == 6*sigma(m), write("b067065.txt", n++, " ", m); if (n==1000, return)) ) } \\ Harry J. Smith, May 03 2010
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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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