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A067766
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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.
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1
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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
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OFFSET
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1,1
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LINKS
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MATHEMATICA
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Select[Range[600], DivisorSigma[1, #]^2>4*DivisorSigma[2, #]&] (* Harvey P. Dale, Dec 27 2015 *)
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PROG
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(PARI) for(n=1, 1000, if(sigma(n)^2>4*sumdiv(n, k, k^2), print1(n, ", ")))
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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