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Search: id:A096490
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| A096490 |
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Numbers x satisfying condition: sigma[2,x]/x^2 >=3/2, where sigma[2,x] is the sum of square of divisors of x. |
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+0
2
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| 60, 120, 168, 180, 240, 252, 300, 336, 360, 420, 480, 504, 540, 600, 660, 672, 720, 756, 780, 792, 840, 900, 924, 936, 960, 1008, 1020, 1080, 1140, 1176, 1200, 1260, 1320, 1344, 1380, 1440, 1500, 1512, 1560, 1584, 1620, 1680, 1740, 1764, 1800, 1848, 1860
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OFFSET
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1,1
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COMMENT
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A056866 seems to be a proper subset of this sequence. E.g. 5616 is present in both sequence, but 252 is only here.
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EXAMPLE
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n=60: 1+4+9+16+25+36+100+144+225+400+900+3600=5460>1.5*3600=5400
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MATHEMATICA
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Do[s=DivisorSigma[2, n]/(n^2); If[Greater[s, 3/2], Print[n]], {n, 1, 10000}]
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CROSSREFS
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Cf. A001157, A056866.
Sequence in context: A039398 A044001 A008887 this_sequence A056866 A098136 A060793
Adjacent sequences: A096487 A096488 A096489 this_sequence A096491 A096492 A096493
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Jun 25 2004
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