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 A023197 Numbers k such that sigma(k) >= 3*k. 15
 120, 180, 240, 360, 420, 480, 504, 540, 600, 660, 672, 720, 780, 840, 900, 960, 1008, 1080, 1200, 1260, 1320, 1344, 1440, 1512, 1560, 1584, 1620, 1680, 1800, 1848, 1872, 1890, 1920, 1980, 2016, 2040, 2100, 2160, 2184, 2280, 2340, 2352, 2376, 2400, 2520 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Sometimes called 3-abundant numbers (but compare the comments in A033880). The first odd number is A119240(3) = 1018976683725. - T. D. Noe, Mar 31 2011 REFERENCES Melvyn B. Nathanson, Elementary Methods in Number Theory, Springer, 2000, p 260. LINKS T. D. Noe, Table of n, a(n) for n = 1..10000 MAPLE select(t -> numtheory:-sigma(t) >= 3*t, [\$1..10000]); # Robert Israel, Dec 28 2014 MATHEMATICA Select[Range[10000], DivisorSigma[1, #] >= 3*#&] (* Vladimir Joseph Stephan Orlovsky, Apr 21 2010 *) CROSSREFS Cf. A119240. See A033880 for definition of k-abundancy. Sequence in context: A189975 A232461 A090782 * A204828 A204830 A279088 Adjacent sequences:  A023194 A023195 A023196 * A023198 A023199 A023200 KEYWORD nonn AUTHOR STATUS approved

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Last modified August 13 00:27 EDT 2020. Contains 336441 sequences. (Running on oeis4.)