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 A243306 #9 Sep 08 2022 08:46:08
%S A243306 1,1,2,2,12,2,58,12,58,12,1014,12,4084,58,248,248,65520,58,262126,248,
%T A243306 4084,1014,4194282,248,1048556,4084,262126,4084,268435428,248,
%U A243306 1073741794,65520,1048556,65520,16777192,4084,68719476700,262126,16777192,65520
%N A243306 2^phi(n) - phi(n).
%H A243306 Vincenzo Librandi, <a href="/A243306/b243306.txt">Table of n, a(n) for n = 1..1000</a>
%F A243306 a(n) = A066781(n) - A000010(n). - _Wesley Ivan Hurt_, Jun 04 2014
%p A243306 with(numtheory); A243306:=n->2^phi(n)-phi(n); seq(A243306(n), n=1..50); # _Wesley Ivan Hurt_, Jun 04 2014
%t A243306 Table[2^EulerPhi[n] - EulerPhi[n], {n, 1, 50}]
%t A243306 2^#-#&/@EulerPhi[Range[50]] (* _Harvey P. Dale_, Dec 19 2017 *)
%o A243306 (Magma) [2^EulerPhi(n)-EulerPhi(n): n in [1..40]];
%Y A243306 Cf. A066781, A100371.
%K A243306 nonn
%O A243306 1,3
%A A243306 _Vincenzo Librandi_, Jun 04 2014