%I #27 Jun 17 2024 15:46:28
%S 4,12,56,216,1240,5040,31992,139968,828576,3720000,25238048,104509440,
%T 803499840,3687014016,24373440000,110630707200,790546192128,
%U 3463116249600,25522921047520,108957312000000,816244048599840,3924124012353600,26682733370563200
%N a(n) = phi(6^n-1)/n, where phi is Euler's totient function (A000010).
%H Seiichi Manyama, <a href="/A295496/b295496.txt">Table of n, a(n) for n = 1..100</a>
%H Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/TotientFunction.html">Totient Function</a>.
%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Euler%27s_totient_function">Euler's totient function</a>.
%t Array[EulerPhi[6^# - 1]/# &, 25] (* _Paolo Xausa_, Jun 17 2024 *)
%o (PARI) {a(n) = eulerphi(6^n-1)/n}
%Y Column k=6 of A369291.
%Y phi(k^n-1)/n: A011260 (k=2), A027385 (k=3), A027695 (k=4), A027741 (k=5), this sequence (k=6), A027743 (k=7), A027744 (k=8), A027745 (k=9), A295497 (k=10), A319166 (k=11).
%K nonn
%O 1,1
%A _Seiichi Manyama_, Nov 22 2017