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 A362664 #8 Apr 29 2023 07:34:06 %S A362664 1,2,3,4,10,15,20,22,28,42,44,45,46,52,54,56,58,70,78,82,92,100,102, %T A362664 104,106,116,130,136,140,148,162,164,166,172,174,178,184,190,196,200, %U A362664 204,208,212,220,222,226,228,234,238,246,250,255,260,262,268,272,282,292,296 %N A362664 Numbers k with exactly two solutions x to the equation iphi(x) = k, where iphi is the infinitary totient function A091732. %C A362664 Numbers k such that A362485(k) = 2. %C A362664 There are no numbers k with a single solution to iphi(x) = k, because if iphi(x) = k, and A007814(x) is even, then 2*x is also a solution, i.e., iphi(2*x) = k. %H A362664 Amiram Eldar, <a href="/A362664/b362664.txt">Table of n, a(n) for n = 1..10000</a> %t A362664 Select[Range[300], Length[invIPhi[#]] == 2 &] (* using the function invIPhi from A362484 *) %Y A362664 Cf. A007814, A091732, A362484, A362485. %Y A362664 Similar sequences: A361969, A362185. %K A362664 nonn %O A362664 1,2 %A A362664 _Amiram Eldar_, Apr 29 2023