A366623 a(n) = phi(6^n-1), where phi is Euler's totient function (A000010).

4, 24, 168, 864, 6200, 30240, 223944, 1119744, 7457184, 37200000, 277618528, 1254113280, 10445497920, 51618196224, 365601600000, 1770091315200, 13439285266176, 62336092492800, 484935499902880, 2179146240000000, 17141125020596640, 86330728271779200

Offset: 1

Author

Sean A. Irvine, Oct 14 2023

Keywords

• nonn

Links

• Max Alekseyev, Table of n, a(n) for n = 1..430

Crossrefs

phi(k^n-1): A053287 (k=2), A295500 (k=3), A295501 (k=4), A295502 (k=5), this sequence (k=6), A366635 (k=7), A366654 (k=8), A366663 (k=9), A295503 (k=10), A366685 (k=11), A366711 (k=12).

Cf. A024062, A000010, A295502, A366620, A366621, A366622.

Programs

Mathematica

EulerPhi[6^Range[22] - 1] (* Paul F. Marrero Romero, Oct 23 2023 *)

PARI

{a(n) = eulerphi(6^n-1)}

Formula

a(n) = A000010(A024062(n)). - Paul F. Marrero Romero, Oct 23 2023