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 A361969 #11 Apr 02 2023 05:56:11 %S A361969 3,7,14,15,31,54,62,63,127,154,174,182,186,234,246,254,255,294,308, %T A361969 318,322,364,406,414,496,510,511,516,534,558,574,594,644,666,678,762, %U A361969 804,806,812,846,870,948,1022,1023,1026,1036,1074,1098,1146,1148,1164,1204,1246 %N A361969 Numbers k with a single solution x to the equation uphi(x) = k, where uphi is the unitary totient function (A047994). %C A361969 Numbers k such that A361967(k) = 1. %C A361969 According to Carmichael's totient function conjecture, there are no numbers with a single solution x to the corresponding equation phi(x) = k, with Euler's totient function (A000010). %C A361969 A000225(m) = 2^m - 1 is a term for all m >= 2. These are the only odd terms. %H A361969 Amiram Eldar, <a href="/A361969/b361969.txt">Table of n, a(n) for n = 1..10000</a> %H A361969 Wikipedia, <a href="https://en.wikipedia.org/wiki/Carmichael%27s_totient_function_conjecture">Carmichael's totient function conjecture</a>. %t A361969 Select[Range[1250], Length[invUPhi[#]] == 1 &] (* using the function invUPhi from A361966 *) %Y A361969 Cf. A000010, A000225, A047994, A135347, A361966, A361967, A361968, A361970, A361971. %K A361969 nonn %O A361969 1,1 %A A361969 _Amiram Eldar_, Apr 01 2023