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 A319183 #30 Jan 31 2024 20:50:21
%S A319183 1,4,32,280,5040,37856,829440,15676416,589032000,10374307328,
%T A319183 388566097920,7619466454080,390751784579520,11138729990400000,
%U A319183 575561351791902720,24328359845627701248,1640651748984970444800,34709116765970413844280,2459108342476800000000000
%N A319183 a(n) = phi(n^n - 1)/n where phi is A000010.
%C A319183 Main diagonal of the array T(n,k) = phi(n^k-1)/k for n > 1 and k > 1, which starts
%C A319183 1, 2, 2, 6, 6, 18, 16, ... A011260
%C A319183 2, 4, 8, 22, 48, 156, 320, ... A027385
%C A319183 4, 12, 32, 120, 288, 1512, 4096, ... A027695
%C A319183 4, 20, 48, 280, 720, 5580, 14976, ... A027741
%C A319183 12, 56, 216, 1240, 5040, 31992, 139968, ... A295496
%C A319183 8, 36, 160, 1120, 6048, 37856, 192000, ... A027743
%C A319183 18, 144, 432, 5400, 23328, 254016, 829440, ... A027744
%H A319183 Seiichi Manyama, <a href="/A319183/b319183.txt">Table of n, a(n) for n = 2..50</a>
%H A319183 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/TotientFunction.html">Totient Function</a>.
%H A319183 Wikipedia, <a href="https://en.wikipedia.org/wiki/Euler%27s_totient_function">Euler's totient function</a>.
%t A319183 Table[EulerPhi[n^n-1]/n,{n,20}] (* _Harvey P. Dale_, Aug 04 2020 *)
%o A319183 (PARI) {a(n) = eulerphi(n^n-1)/n}
%Y A319183 A diagonal of A369291.
%Y A319183 Cf. A000010, A006486, A027385.
%K A319183 nonn
%O A319183 2,2
%A A319183 _Seiichi Manyama_, Sep 12 2018