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A067701
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n satisfying phi(n-1) + phi(n+1) = phi(2n).
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2
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5, 7, 25, 77, 217, 305, 3665, 4645, 5065, 8815, 12205, 12545, 19877, 20435, 24235, 29545, 37735, 47995, 60115, 72085, 73025, 77045, 87475, 121145, 126055, 129245, 149755, 190267, 234635, 247855, 273295, 275723, 419365, 531235, 553475, 621725
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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EXAMPLE
| phi(25-1) + phi(25+1) = 8+12 = phi(2*25), so 25 is in the sequence.
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MATHEMATICA
| Select[Range[10^5], EulerPhi[ # - 1] + EulerPhi[ # + 1] == EulerPhi[2# ] &]
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CROSSREFS
| Cf. A000010.
Cf. A066231.
Sequence in context: A100095 A179782 A013626 * A059240 A166100 A135606
Adjacent sequences: A067698 A067699 A067700 * A067702 A067703 A067704
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KEYWORD
| nonn
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AUTHOR
| Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Feb 05 2002
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EXTENSIONS
| Edited by Dean Hickerson (dean.hickerson(AT)yahoo.com), Feb 12 2002
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