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Search: id:A066290
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| A066290 |
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Numbers n such that Mod[DivisorSigma[4k-2,n],n]=0 holds presumably for all k; that is (4k-2)-power-sums of divisors of n are divisible by n for all k. |
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2
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| 1, 10, 60, 65, 130, 150, 260, 780, 1105, 2210, 4420, 8840, 13260, 19720, 20737, 32045, 41474, 55250, 64090, 82948, 103685, 128180, 207370, 207553, 221000, 248844, 256360, 295800, 331500, 352529, 384540, 414740, 415106, 450840, 512720
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OFFSET
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1,2
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FORMULA
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DivisorSigma[4k-2, n]/n] is integer for all k=1, 2, 3, .., 200, ...
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EXAMPLE
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Tested for each n and k<200. Proof for several k seems not so tedious because number of divisors of terms of sequence is not so large: {1, 4, 12, 4, 8, 12, 12, 24, 8, 16, 24, 32, 48, 32, 4, 16, 8, 32, 32, 12, 8, 48, 16, 8, 64, 24, 64, 96, 96, 8, 96, 24, 16, 96, 80, 16, 32, 24}.
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CROSSREFS
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Cf. A066135, A066284, A066289.
Sequence in context: A140890 A055714 A046762 this_sequence A065641 A121874 A076160
Adjacent sequences: A066287 A066288 A066289 this_sequence A066291 A066292 A066293
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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), Dec 12 2001
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