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Search: id:A066177
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| A066177 |
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Numbers n such that sigma(n+1)-sigma(n) = -sigma(n)/d(n), where d(n) denotes the number of divisors of n. |
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1
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| 165, 1106, 7006, 11516, 12597, 14882, 16604, 21045, 23541, 39866, 42465, 43172, 46078, 67198, 95588
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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These are the n at which the divisor sum, sigma(n), is decreasing at a rate equal to the average divisor size, sigma(n)/d(n).
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EXAMPLE
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sigma(165)-sigma(166) = 288-252 = 36 = 288/8 = sigma(165)/d(165).
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MATHEMATICA
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Select[ Range[ 1, 10^5 ], DivisorSigma[ 1, # ]-DivisorSigma[ 1, #+1 ]==DivisorSigma[ 1, # ]/DivisorSigma[ 0, # ] & ]
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CROSSREFS
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Sequence in context: A029563 A135806 A124409 this_sequence A027796 A105944 A071576
Adjacent sequences: A066174 A066175 A066176 this_sequence A066178 A066179 A066180
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KEYWORD
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nonn
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AUTHOR
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Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Dec 14 2001
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