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Search: id:A066172
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| A066172 |
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Numbers n such that EulerPhi(n+1) - EulerPhi(n) = -d(n). |
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+0
1
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| 5, 7, 33, 135, 231, 273, 435, 465, 824, 6375, 17115, 33704, 86355, 207315, 469395, 603585
(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 EulerPhi(n) is decreasing at a rate equal to d(n).
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EXAMPLE
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EulerPhi(6) - EulerPhi(5) = 2 - 4 = -2 = -d(5).
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MATHEMATICA
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Select[ Range[ 1, 10^6 ], EulerPhi[ # ] - EulerPhi[ # + 1 ] == DivisorSigma[ 0, # ] & ]
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CROSSREFS
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Adjacent sequences: A066169 A066170 A066171 this_sequence A066173 A066174 A066175
Sequence in context: A153414 A104815 A007911 this_sequence A018353 A081851 A006067
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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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