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 A225983 #18 Aug 08 2020 08:22:54
%S A225983 1,2,4,16,25,64,81,100,121,256,289,484,529,729,841,1024,1156,1296,
%T A225983 1600,1681,2116,2209,2401,2809,3025,3364,3481,4096,4624,5041,5184,
%U A225983 6400,6724,6889,7225,7744,7921,8464,8836,10201,11236,11449,11664,12100,12769,13225
%N A225983 Numbers k such that gcd(phi(k), tau(k)) = 1.
%H A225983 Amiram Eldar, <a href="/A225983/b225983.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..100 from Paolo P. Lava, terms 101..1000 from T. D. Noe)
%e A225983 If n = 13924 then phi(n) = 6844 = 2^2*29*59 and tau(n) = 9 = 3^2. There is no common prime factor.
%p A225983 with(numtheory); A225983:=proc(q) local n;
%p A225983 for n from 1 to q do if gcd(tau(n),phi(n))=1 then print(n);
%p A225983 fi; od; end: A225983(10^6);
%t A225983 t = {}; n = 0; While[Length[t] < 100, n++; If[GCD[EulerPhi[n], DivisorSigma[0, n]] == 1, AppendTo[t, n]]]; t (* _T. D. Noe_, May 22 2013 *)
%Y A225983 Cf. A000005, A000010, A046678, A055008.
%K A225983 nonn
%O A225983 1,2
%A A225983 _Paolo P. Lava_, May 22 2013