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 A226386 #12 Dec 13 2013 11:11:31
%S A226386 5,10,13,15,17,19,20,21,26,29,30,33,34,35,37,38,39,40,41,42,45,51,52,
%T A226386 53,55,57,58,60,61,63,65,66,68,69,70,73,74,76,77,78,80,82,84,85,87,89,
%U A226386 90,91,93,95,97,101,102,104,105,106,109,110,111,113,114,115
%N A226386 Numbers n such that rad(phi(n)) < phi(rad(n)), where rad(n) is the squarefree kernel of n, and phi is Euler's totient function.
%H A226386 Charles R Greathouse IV, <a href="/A226386/b226386.txt">Table of n, a(n) for n = 1..10000</a>
%t A226386 rad[n_] := Product[fa[n][[i, 1]], {i, Length[fa[n]]}]; fa = FactorInteger; Select[Range[500], rad[EulerPhi[#]] < EulerPhi[rad[#]] &]
%o A226386 (PARI) rad(n)=my(f=factor(n)[,1]);prod(i=1,#f,f[i])
%o A226386 is(n)=my(f=factor(n)[,1],r=prod(i=1,#f,f[i]),ph=prod(i=1,#f,f[i]-1)*n/r); rad(ph)<eulerphi(r) \\ _Charles R Greathouse IV_, Dec 13 2013
%Y A226386 Cf. A007947, A000010, A226384.
%K A226386 nonn
%O A226386 1,1
%A A226386 _José María Grau Ribas_, Jun 05 2013