This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A279011 #26 Jul 07 2025 15:58:45
%S A279011 1,2,12,152,222,268,362,432,723,992,1517,2532,2567,8472,9718,9858,
%T A279011 13498,15738,34732,35898,44092,60363,69312,75168,75973,82752,87208,
%U A279011 88888,98198,105852,114392,126848,128672,135368,141093,161268,221223,233788,301513,328358
%N A279011 Numbers k such that phi(6k) is either phi(6k-2) or phi(6k+2), where phi is Euler's totient function A000010.
%H A279011 Amiram Eldar, <a href="/A279011/b279011.txt">Table of n, a(n) for n = 1..1554</a>
%H A279011 Dov Jarden, <a href="/A001602/a001602.pdf">Recurring Sequences</a>, Riveon Lematematika, Jerusalem, 1966. [Annotated scanned copy] See p. 67.
%t A279011 Select[Range[10^6], Function[k, Or @@ Map[EulerPhi[6 k] == EulerPhi@ # &, 6 k + {-2, 2}]]] (* _Michael De Vlieger_, Dec 12 2016 *)
%t A279011 Select[Range[330000],EulerPhi[6#]==EulerPhi[6#-2]||EulerPhi[6#]==EulerPhi[6#+2]&] (* _Harvey P. Dale_, Jul 07 2025 *)
%o A279011 (Magma) [n: n in [1..1000000] | not (EulerPhi(6*n) eq EulerPhi(6*n-2)) eq (EulerPhi(6*n) eq EulerPhi(6*n+2))]; // _Vincenzo Librandi_, Dec 12 2016
%Y A279011 Cf. A000010.
%Y A279011 Union of A279183 and A279184.
%K A279011 nonn
%O A279011 1,2
%A A279011 _N. J. A. Sloane_, Dec 10 2016
%E A279011 More terms from _Vincenzo Librandi_, Dec 12 2016