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A092272
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Numbers n such that phi(n)=phi(2*n+1).
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1
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97, 1417, 2593, 107167, 128137, 262993, 468247, 629821, 879937, 894127, 1100347, 1260847, 1620307, 1644967, 1897417, 2890717, 3122773, 3186397, 3651667, 4169197, 6176467, 7072477, 7344187, 8237707, 8974717, 9254647, 13032547
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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EXAMPLE
| phi(97)=97-1=96=2*4*12=phi(3*5*13)=phi(195)=phi(2*97+1)
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MAPLE
| with (numtheory): for i from 1 to 1000000 do if phi(i)=phi(2*i+1) then print(i) fi; od;
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MATHEMATICA
| Do[ If[ EulerPhi[n] == EulerPhi[2n + 1], Print[n]], {n, 1, 15540036}] (from Robert G. Wilson v Feb 20 2004)
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CROSSREFS
| Cf. A000010, A005384.
Sequence in context: A087596 A133836 A038532 * A162542 A020538 A075665
Adjacent sequences: A092269 A092270 A092271 * A092273 A092274 A092275
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KEYWORD
| nonn
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AUTHOR
| Pooya Farshim (P.Farshim.00(AT)cantab.net), Feb 17 2004
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EXTENSIONS
| More terms from Labos E. (labos(AT)ana.sote.hu) and Robert G. Wilson v (rgwv(AT)rgwv.com), Feb 19 2004
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