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A279184 Numbers k such that phi(6k) = phi(6k+2), where phi is Euler's totient function A000010. 3
268, 723, 9718, 9858, 13498, 15738, 35898, 60363, 75168, 75973, 87208, 88888, 98198, 126848, 135368, 141093, 161268, 221223, 233788, 301513, 328358, 330633, 419148, 507648, 527928, 543468, 551238, 556418, 586018, 725958, 772508, 964588, 985728 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..33.

Dov Jarden, Recurring Sequences, Riveon Lematematika, Jerusalem, 1966. [Annotated scanned copy] See p. 67.

MAPLE

select( k -> numtheory:-phi(6*k)=numtheory:-phi(6*k+2), [$1..10^6]); # Robert Israel, Dec 11 2016

MATHEMATICA

a = {}; Do[If[EulerPhi[6 k] == 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: A096613 A234878 A194774 * A237228 A190352 A235175

Adjacent sequences:  A279181 A279182 A279183 * A279185 A279186 A279187

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Dec 10 2016

EXTENSIONS

a(8)-a(33) from Robert Israel, Dec 11 2016

STATUS

approved

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Last modified September 25 19:48 EDT 2017. Contains 292500 sequences.