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 A049196 #17 Sep 08 2022 08:44:58
%S A049196 1,2,3,6,7,11,14,22,23,31,43,46,47,59,62,67,71,79,83,86,94,103,107,
%T A049196 118,131,134,139,142,158,166,167,179,191,206,211,214,223,227,239,262,
%U A049196 263,278,283,311,331,334,347,358,359,367,382,383,419,422,431,439,443,446
%N A049196 Squarefree numbers whose Euler totient function is also squarefree.
%H A049196 Amiram Eldar, <a href="/A049196/b049196.txt">Table of n, a(n) for n = 1..10000</a>
%F A049196 k such that abs(mu(k)) = 1 and abs(mu(phi(k))) = 1.
%e A049196 86 is here because it is squarefree and the same holds for phi(86) = 42.
%t A049196 Select[Range[500],And@@SquareFreeQ/@{#,EulerPhi[#]}&] (* _Harvey P. Dale_, Nov 05 2013 *)
%o A049196 (Magma) [n:n in [1..500]| IsSquarefree(n) and IsSquarefree(EulerPhi(n))]; // _Marius A. Burtea_, Jul 11 2019
%o A049196 (PARI) isok(m) = issquarefree(m) && issquarefree(eulerphi(m)); \\ _Michel Marcus_, Jul 12 2019
%Y A049196 A000010, A005117, A013929.
%K A049196 nonn
%O A049196 1,2
%A A049196 _Labos Elemer_