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A067766 Numbers n such that sigma(n)^2>4*sigma_2(n) where sigma_2(n) is the sum of squares over the divisors of n. 1
24, 36, 48, 60, 72, 84, 90, 96, 108, 120, 126, 132, 140, 144, 150, 156, 160, 168, 180, 192, 204, 210, 216, 228, 240, 252, 264, 270, 276, 280, 288, 300, 312, 320, 324, 330, 336, 360, 378, 384, 390, 396, 400, 408, 420, 432, 440, 450, 456, 462, 468, 480, 504 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

MATHEMATICA

Select[Range[600], DivisorSigma[1, #]^2>4*DivisorSigma[2, #]&] (* Harvey P. Dale, Dec 27 2015 *)

PROG

(PARI) for(n=1, 1000, if(sigma(n)^2>4*sumdiv(n, k, k^2), print1(n, ", ")))

CROSSREFS

Sequence in context: A054775 A273088 A334674 * A306776 A300794 A327945

Adjacent sequences:  A067763 A067764 A067765 * A067767 A067768 A067769

KEYWORD

easy,nonn

AUTHOR

Benoit Cloitre, Apr 04 2002

STATUS

approved

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Last modified October 19 09:08 EDT 2021. Contains 348074 sequences. (Running on oeis4.)