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A279183
Numbers k such that phi(6k) = phi(6k-2), where phi is Euler's totient function A000010.
3
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
OFFSET
1,2
LINKS
Dov Jarden, Recurring Sequences, Riveon Lematematika, Jerusalem, 1966. [Annotated scanned copy] See p. 67.
MATHEMATICA
a = {}; Do[If[EulerPhi[6k] == EulerPhi[6 k - 2], AppendTo[a, k]], {k, 1000000}]; a (* Vincenzo Librandi, Dec 11 2016 *)
PROG
(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
CROSSREFS
A279011 is the union of A279183 and A279184. Cf. A000010.
Sequence in context: A374869 A340026 A279011 * A126777 A126345 A229558
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Dec 10 2016
EXTENSIONS
More terms from Vincenzo Librandi, Dec 11 2016
STATUS
approved