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A088011 Even and odd solutions to abs(sigma(x)-2x) <= log(x). Numbers n whose abundance-radius does not exceed log(n). 2
4, 6, 8, 10, 16, 20, 28, 32, 64, 70, 88, 104, 110, 128, 136, 152, 256, 464, 496, 512, 592, 650, 884, 1024, 1155, 1888, 1952, 2048, 2144, 4030, 4096, 5830, 8128, 8192, 8384, 8925, 11096, 16384, 17816, 18632, 18904, 32128, 32445, 32768, 32896, 33664, 45356 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

See A088012 for the subsequence of odd terms, only 7 being known up to 10^13. - M. F. Hasler, Feb 21 2017

LINKS

Table of n, a(n) for n=1..47.

MATHEMATICA

abu[x_] := Abs[DivisorSigma[1, x]-2*x] Do[If[ !Greater[abu[n], Log[n]//N], Print[n]], {n, 1, 100000}]

PROG

(PARI) (is(n)=abs(sigma(n)-2*n)<log(n)); select(is, [1..5000]) \\ M. F. Hasler, Feb 21 2017

CROSSREFS

Cf. A088007-A088012, A077374, A005100, A005101, A000079, A000396.

Sequence in context: A062711 A280739 A117347 * A289424 A050835 A294243

Adjacent sequences:  A088008 A088009 A088010 * A088012 A088013 A088014

KEYWORD

nonn

AUTHOR

Labos Elemer, Oct 20 2003

STATUS

approved

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Last modified April 25 21:06 EDT 2019. Contains 322461 sequences. (Running on oeis4.)