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 A366630 #18 Apr 21 2025 03:19:12
%S A366630 1,6,36,180,1296,6000,41472,230496,1580800,8359200,58579200,310968900,
%T A366630 2175102720,10971642240,76065091200,351048600000,2811459796992,
%U A366630 14508487949472,88870766837760,522016066337712,3564233663616000,17479898551382400,128060205344805888
%N A366630 a(n) = phi(6^n+1), where phi is Euler's totient function (A000010).
%H A366630 Max Alekseyev, <a href="/A366630/b366630.txt">Table of n, a(n) for n = 0..430</a>
%F A366630 a(n) = A000010(A062394(n)). - _Paul F. Marrero Romero_, Oct 17 2023
%t A366630 EulerPhi[6^Range[0, 22] + 1] (* _Paul F. Marrero Romero_, Oct 17 2023 *)
%o A366630 (PARI) {a(n) = eulerphi(6^n+1)}
%Y A366630 Cf. A062394, A000010, A366623, A366618, A366627, A366628, A366629, A366670.
%Y A366630 Cf. A053285, A366579, A366608, A366639, A366658, A366667, A366669, A366690, A366716.
%K A366630 nonn
%O A366630 0,2
%A A366630 _Sean A. Irvine_, Oct 14 2023