A366658 a(n) = phi(8^n+1), where phi is Euler's totient function (A000010).

1, 6, 48, 324, 3840, 19800, 186624, 1365336, 16515072, 84768120, 760320000, 5632621632, 64258375680, 366369658200, 3105655160832, 20140520400000, 280012271910912, 1495522910085120, 12824556668190720, 95907982079387520, 1080582572777472000, 5688765822212629632

Offset

0,2

Links

Max Alekseyev, Table of n, a(n) for n = 0..502

Formula

a(n) = A000010(A062395(n)). - Paul F. Marrero Romero, Nov 06 2023

a(n) = A053285(3*n). - Max Alekseyev, Jan 09 2024

Mathematica

EulerPhi[8^Range[0, 21] + 1] (* Paul F. Marrero Romero, Oct 17 2023 *)

Prog

(PARI) {a(n) = eulerphi(8^n+1)}
(Python)
from sympy import totient
def A366658(n): return totient((1<<3*n)+1) # Chai Wah Wu, Oct 15 2023

Crossrefs

Cf. A062395, A000010, A057936, A274905, A366654, A366655, A366656, A366657, A366671.

Cf. A053285, A366579, A366608, A366618, A366630, A366639, A366667, A366669, A366690, A366716.

Sequence in context: A165758 A166152 A300582 * A049316 A320072 A024075

Adjacent sequences: A366655 A366656 A366657 * A366659 A366660 A366661

Keyword

nonn

Author

Sean A. Irvine, Oct 15 2023

Status

approved