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Search: id:A066198
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| A066198 |
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Numbers n where EulerPhi changes as fast as sigma, i.e. |EulerPhi(n+1)-EulerPhi(n)| = |sigma(n+1)-sigma(n)|. |
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+0
5
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| 2, 6, 8, 10, 22, 46, 58, 82, 106, 166, 178, 188, 226, 262, 285, 346, 358, 382, 466, 478, 502, 562, 586, 718, 838, 854, 862, 886, 902, 982, 1018, 1186, 1282, 1306, 1318, 1366, 1438, 1486, 1522, 1618, 1822, 1906, 2013, 2026, 2038, 2062, 2098, 2206, 2446, 2458
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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This sequence is the union of two sequences A145748 and A145749. See comment lines of A145749. [From Farideh Firoozbakht (mymontain(AT)yahoo.com), Nov 01 2008]
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EXAMPLE
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|EulerPhi(7)-EulerPhi(6)| = |6-2| = |8-12| = |sigma(7)-sigma(6)|.
|EulerPhi(9)-EulerPhi(8)|=||6-4|=2=|13-15|=|sigma(9)-sigma(8)|.
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MATHEMATICA
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Select[ Range[ 1, 10^4 ], Abs[ DivisorSigma[ 1, # + 1 ] - DivisorSigma[ 1, # ] ] == Abs[ EulerPhi[ # + 1 ] - EulerPhi[ # ] ] & ]
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CROSSREFS
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Cf. A065387, A145748, A145749. [From Farideh Firoozbakht (mymontain(AT)yahoo.com), Nov 01 2008]
Sequence in context: A038619 A118257 A066762 this_sequence A108417 A166064 A144675
Adjacent sequences: A066195 A066196 A066197 this_sequence A066199 A066200 A066201
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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 16 2001
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EXTENSIONS
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More terms from Jason Earls (zevi_35711(AT)yahoo.com), Jun 05 2002
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