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%I #19 Sep 08 2022 08:46:18
%S 268,723,9718,9858,13498,15738,35898,60363,75168,75973,87208,88888,
%T 98198,126848,135368,141093,161268,221223,233788,301513,328358,330633,
%U 419148,507648,527928,543468,551238,556418,586018,725958,772508,964588,985728
%N Numbers k such that phi(6k) = phi(6k+2), where phi is Euler's totient function A000010.
%H Dov Jarden, <a href="/A001602/a001602.pdf">Recurring Sequences</a>, Riveon Lematematika, Jerusalem, 1966. [Annotated scanned copy] See p. 67.
%p select( k -> numtheory:-phi(6*k)=numtheory:-phi(6*k+2), [$1..10^6]); # _Robert Israel_, Dec 11 2016
%t a = {}; Do[If[EulerPhi[6 k] == EulerPhi[6 k + 2], AppendTo[a, k]], {k, 1000000}]; a (* _Vincenzo Librandi_, Dec 11 2016 *)
%o (Magma) [n: n in [1..2*10^6] | EulerPhi(6*n) eq EulerPhi(6*n+2)]; // _Vincenzo Librandi_, Dec 11 2016
%o (PARI) isok(k) = eulerphi(6*k) == eulerphi(6*k+2); \\ _Michel Marcus_, Dec 11 2016
%Y A279011 is the union of A279183 and A279184. Cf. A000010.
%K nonn
%O 1,1
%A _N. J. A. Sloane_, Dec 10 2016
%E a(8)-a(33) from _Robert Israel_, Dec 11 2016
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