A088010 - OEIS

A088010

Odd numbers k such that abs(sigma(k)-2k) <= k^(1/3). Abundance-radius = abs(sigma(k)-2k) does not exceed cubic root of k and k is odd.

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

1,2

LINKS

Alexander Violette, Table of n, a(n) for n = 1..157 (terms 1...100 from Donovan Johnson)

MATHEMATICA

abu[x_] := Abs[DivisorSigma[1, x]-2*x] Do[If[ !Greater[abu[n], n^(1/3)//N]&&OddQ[n], Print[n]], {n, 1, 100000}]

PROG

(PARI) isok(n) = (n % 2) && (abs(sigma(n)-2*n) <= sqrtn(n, 3)); \\ Michel Marcus, Nov 10 2017

CROSSREFS

Cf. A077374, A088007, A088008, A088011, A088012, A000396, A000079, A005100, A005101.

Sequence in context: A087415 A184477 A184469 * A145753 A184468 A231760

Adjacent sequences: A088007 A088008 A088009 * A088011 A088012 A088013

KEYWORD

nonn

AUTHOR

Labos Elemer, Oct 20 2003

EXTENSIONS

a(17)-a(28) from Donovan Johnson, Feb 01 2009

STATUS

approved