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 A193386 #16 Dec 05 2017 04:08:41
%S A193386 0,0,1,1,2,1,2,2,2,2,2,2,4,2,3,3,4,2,3,3,4,2,2,3,4,4,3,4,4,3,4,4,4,4,
%T A193386 6,4,6,3,6,4,6,4,4,4,6,2,2,4,4,4,5,6,4,3,6,6,6,4,2,4,8,4,6,5,8,4,4,5,
%U A193386 4,6,4,6,9,6,6,6,8,6,4,5,4,6,2,6,6,4,6,6,6,6,9,4,8,2,9,5,10,4,8,6,6,5,4,8,8
%N A193386 Number of even divisors of phi(n).
%H A193386 Antti Karttunen, <a href="/A193386/b193386.txt">Table of n, a(n) for n = 1..16384</a>
%F A193386 a(n) = A183063(A000010(n)) = A062821(n) - A193453(n). - _Antti Karttunen_, Dec 04 2017
%e A193386 a(13) = 4 because phi(13) = 12 and the 4 even divisors are { 2, 4, 6, 12}.
%t A193386 f[n_] := Block[{d = Divisors[EulerPhi[n]]}, Count[EvenQ[d], True]]; Table[f[n], {n, 80}]
%t A193386 (* Second program: *)
%t A193386 Array[DivisorSum[EulerPhi@ #, 1 &, EvenQ] &, 105] (* _Michael De Vlieger_, Dec 04 2017 *)
%o A193386 (PARI) A193386(n) = sumdiv(eulerphi(n), d, 1-(d%2)); \\ _Antti Karttunen_, Dec 04 2017
%Y A193386 Cf. A000010, A062821, A183063, A191613, A193453.
%K A193386 nonn
%O A193386 1,5
%A A193386 _Michel Lagneau_, Jul 25 2011
%E A193386 More terms from _Antti Karttunen_, Dec 04 2017