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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..36.

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: A322399 A340026 A279011 * A126777 A126345 A229558

Adjacent sequences:  A279180 A279181 A279182 * A279184 A279185 A279186

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Dec 10 2016

EXTENSIONS

More terms from Vincenzo Librandi, Dec 11 2016

STATUS

approved

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Last modified August 1 07:45 EDT 2021. Contains 346384 sequences. (Running on oeis4.)