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 A358051 #19 Dec 04 2022 16:32:44 %S A358051 1,16,1024,2500,5184,50625,65536,160000,331776,810000,3779136,4194304, %T A358051 4691556,5345344,7001316,10240000,16867449,20820969,21233664,27060804, %U A358051 36905625,39062500,51840000,52200625,228765625,241864704,268435456,269879184,300259584,333135504 %N A358051 Squares k such that phi(k) is a cube. %H A358051 Project Euler, <a href="https://projecteuler.net/problem=342">Problem 342. The totient of a square is a cube</a>. %F A358051 a(n) = A114076(n)^2. - _Amiram Eldar_, Oct 27 2022 %t A358051 Select[Range[20000]^2, IntegerQ[Surd[EulerPhi[#], 3]] &] (* _Amiram Eldar_, Oct 27 2022 *) %o A358051 (Python) %o A358051 from sympy.ntheory.factor_ import totient %o A358051 from gmpy2 import * %o A358051 def isok(k): %o A358051 if is_square(k): %o A358051 j = isqrt(k) %o A358051 a,b = iroot(totient(j) * j, 3) %o A358051 return b %o A358051 (PARI) isok(k) = issquare(k) && ispower(eulerphi(k), 3); \\ _Michel Marcus_, Oct 27 2022 %Y A358051 Cf. A000010, A114076. %K A358051 nonn %O A358051 1,2 %A A358051 _Darío Clavijo_, Oct 27 2022