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 A078167 #13 Apr 24 2020 11:01:23
%S A078167 1,2,255,256,272,320,340,384,408,480,510,21845,32768,32896,34816,
%T A078167 34952,40960,41120,43520,43690,49152,49344,52224,52428,61440,61680,
%U A078167 65280,280999,281587,282637,282949,283897,294409,297449,300409,302039,304399
%N A078167 Numbers k such that phi(k) is a perfect 7th power.
%H A078167 Amiram Eldar, <a href="/A078167/b078167.txt">Table of n, a(n) for n = 1..10000</a>
%e A078167 phi of the sequence includes 1, 128, 16384, 279936, etc..; powers arise several times; a(3) = A053576(7) = 255; in sequence rather large jumps arise when power of new numbers appear.
%t A078167 k=7; Do[s=EulerPhi[n]^(1/k); If[IntegerQ[s], Print[n]], {n, 1, 1000000}]
%o A078167 (PARI) is(n)=ispower(eulerphi(n),7) \\ _Charles R Greathouse IV_, Apr 24 2020
%Y A078167 Cf. A039770 (square), A039771 (cube), A078164 (4th), A078165 (5th), A078166 (6th), A078167 (7th, this sequence), A078168 (8th), A078169 (9th), A078170 (10th power), A001317, A053576, A045544, A000010.
%K A078167 nonn
%O A078167 1,2
%A A078167 _Labos Elemer_, Nov 27 2002