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A279183
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Numbers k such that phi(6k) = phi(6k-2), where phi is Euler's totient function A000010.
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3
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1, 2, 12, 152, 222, 362, 432, 992, 1517, 2532, 2567, 8472, 34732, 44092, 69312, 82752, 105852, 114392, 128672, 336992, 350082, 393132, 393552, 462747, 497712, 559872, 665817, 714502, 931432, 968952, 1126602, 1281867, 1389337, 1449992, 1638712, 1694292
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OFFSET
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1,2
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LINKS
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Dov Jarden, Recurring Sequences, Riveon Lematematika, Jerusalem, 1966. [Annotated scanned copy] See p. 67.
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MATHEMATICA
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a = {}; Do[If[EulerPhi[6k] == EulerPhi[6 k - 2], AppendTo[a, k]], {k, 1000000}]; a (* Vincenzo Librandi, Dec 11 2016 *)
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PROG
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(Magma) [n: n in [1..2*10^6] | EulerPhi(6*n) eq EulerPhi(6*n-2)]; // Vincenzo Librandi, Dec 11 2016
(PARI) isok(k) = eulerphi(6*k) == eulerphi(6*k-2); \\ Michel Marcus, Dec 11 2016
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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