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A092272
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Numbers n such that phi(n) = phi(2*n+1).
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3
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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, 15540037, 15673027
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OFFSET
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1,1
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LINKS
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EXAMPLE
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phi(97) = 97-1 = 96 = 2*4*12 = phi(3*5*13) = phi(195) = phi(2*97+1)
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MAPLE
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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
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Do[ If[ EulerPhi[n] == EulerPhi[2n + 1], Print[n]], {n, 1, 15540036}] (* Robert G. Wilson v, Feb 20 2004 *)
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PROG
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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Pooya Farshim (P.Farshim.00(AT)cantab.net), Feb 17 2004
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EXTENSIONS
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STATUS
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approved
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