%I #9 Jan 04 2024 19:15:44

%S 10,120,1560,13440,226200,2021760,32518360,274391040,4534807680,

%T 51953616000,646094232960,4662793175040,97266341877120,

%U 1070382142166400,13666309113600000,109897747141754880,2016918439151095000,17518491733377024000,290436363064202660760

%N a(n) = phi(12^n-1), where phi is Euler's totient function (A000010).

%H Max Alekseyev, <a href="/A366711/b366711.txt">Table of n, a(n) for n = 1..310</a>

%t EulerPhi[12^Range[30] - 1]

%o (PARI) {a(n) = eulerphi(12^n-1)}

%Y phi(k^n-1): A053287 (k=2), A295500 (k=3), A295501 (k=4), A295502 (k=5), A366623 (k=6), A366635 (k=7), A366654 (k=8), A366663 (k=9), A295503 (k=10), A366685 (k=11), this sequence (k=12).

%Y Cf. A000010, A024140, A366707, A366708, A366709, A366710, A366717, A366718.

%K nonn

%O 1,1

%A _Sean A. Irvine_, Oct 17 2023