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A285615 Numbers n such that usigma(n) >= 3n, where usigma(n) = sum of unitary divisors of n (A034448). 5

%I

%S 30030,39270,43890,46410,51870,53130,62790,66990,67830,71610,79170,

%T 82110,84630,85470,91770,94710,99330,101010,103530,108570,111930,

%U 117390,122430,128310,136290,140910,144690,154770,161070,164010,166530,168630,182490,191730

%N Numbers n such that usigma(n) >= 3n, where usigma(n) = sum of unitary divisors of n (A034448).

%C Unitary 3-abundant numbers, correspond to 3-abundant numbers (A023197).

%C Similarly, the first numbers n such that usigma(n) >= 4n are 200560490130, 7420738134810, 8222980095330, and 8624101075590. - _Giovanni Resta_, Apr 23 2017

%H Amiram Eldar, <a href="/A285615/b285615.txt">Table of n, a(n) for n = 1..100</a>

%t usigma[n_] := If[n == 1, 1, Times @@ (1 + Power @@@ FactorInteger[n])]; Select[Range[100000], usigma[#] >= 3*# &]

%Y Cf. A034448, A023197, A034683.

%K nonn

%O 1,1

%A _Amiram Eldar_, Apr 22 2017

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Last modified December 5 06:51 EST 2020. Contains 338944 sequences. (Running on oeis4.)