A279184 Numbers k such that phi(6k) = phi(6k+2), where phi is Euler's totient function A000010.

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

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: A304388 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