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A088010
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Odd numbers n such that abs(sigma(n)-2n) <= n^(1/3). Abundance-radius = abs(sigma(n)-2n) does not exceed cubic root of n and n is odd.
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4
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1, 315, 1155, 8415, 8925, 31815, 32445, 33705, 34335, 78975, 351351, 430815, 437745, 442365, 449295, 730125, 1805475, 7667625, 13800465, 14571585, 16029405, 16286445, 20297745, 20355825, 20487159, 21003885, 22982505, 23082885
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OFFSET
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1,2
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LINKS
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MATHEMATICA
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abu[x_] := Abs[DivisorSigma[1, x]-2*x] Do[If[ !Greater[abu[n], n^(1/3)//N]&&OddQ[n], Print[n]], {n, 1, 100000}]
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PROG
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(PARI) isok(n) = (n % 2) && (abs(sigma(n)-2*n) < sqrtn(n, 3)); \\ Michel Marcus, Nov 10 2017
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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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