%I #22 Dec 15 2024 04:38:10
%S 1,2,12,152,222,362,432,992,1517,2532,2567,8472,34732,44092,69312,
%T 82752,105852,114392,128672,336992,350082,393132,393552,462747,497712,
%U 559872,665817,714502,931432,968952,1126602,1281867,1389337,1449992,1638712,1694292
%N Numbers k such that phi(6k) = phi(6k-2), where phi is Euler's totient function A000010.
%H Amiram Eldar, <a href="/A279183/b279183.txt">Table of n, a(n) for n = 1..761</a>
%H Dov Jarden, <a href="/A001602/a001602.pdf">Recurring Sequences</a>, Riveon Lematematika, Jerusalem, 1966. [Annotated scanned copy] See p. 67.
%t a = {}; Do[If[EulerPhi[6k] == 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 Cf. A000010.
%Y A279011 is the union of A279183 and A279184.
%K nonn
%O 1,2
%A _N. J. A. Sloane_, Dec 10 2016
%E More terms from _Vincenzo Librandi_, Dec 11 2016