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 A328276 #11 Dec 04 2019 09:23:00 %S A328276 3,6,16,85,969 %N A328276 The number of solutions to phi(x) = rad(x)^n, where phi is the Euler totient function (A000010) and rad is the squarefree kernel function (A007947). %C A328276 The author informs me that because there of an error in one of the references, a(4) is > 85. - _N. J. A. Sloane_, Nov 23 2019 %H A328276 Jean-Marie De Konick and Stefan Gubo, <a href="https://www.jstor.org/stable/4145084">When the totient is the product of the squared prime divisors: problem 10966</a>, American Mathematical Monthly, Vol. 111, No. 6 (2004), p. 536. %H A328276 Jean-Marie De Koninck, Florian Luca and A. Sankaranarayanan, <a href="https://projecteuclid.org/euclid.rmjm/1181069489">Positive integers whose Euler function is a power of their kernel function</a>, Rocky Mountain Journal of Mathematics, Vol. 36, No. 1 (2006), pp. 81-96, <a href="https://www.jeanmariedekoninck.mat.ulaval.ca/fileadmin/jmdk/Documents/Publications/2006_positive_integers_whose_euler_function_is_a_power_of_their_kernel_function.pdf">alternative link</a>. %e A328276 a(1) = 3 since there are only 3 solutions to phi(x) = rad(x): x = 1, 4, and 18. %e A328276 a(2) = 6 since there are only 6 solutions to phi(x) = rad(x)^2: x = 1, 8, 108, 250, 6174, and 41154 (the terms of A211413). %Y A328276 Cf. A000010, A007947, A105261, A211413, A328274, A328275. %K A328276 nonn,more %O A328276 1,1 %A A328276 _Amiram Eldar_, Oct 10 2019