A366654 a(n) = phi(8^n-1), where phi is Euler's totient function (A000010).

6, 36, 432, 1728, 27000, 139968, 1778112, 6635520, 113467392, 534600000, 6963536448, 26121388032, 465193834560, 2427720325632, 28548223200000, 109586090557440, 1910296842179040, 9618417501143040, 123523151337020736, 406467072000000000, 7713001620195508224

Offset

1,1

Links

Max Alekseyev, Table of n, a(n) for n = 1..500

Formula

a(n) = A053287(3*n). - Max Alekseyev, Jan 09 2024

Mathematica

EulerPhi[8^Range[30] - 1]

Prog

(PARI) {a(n) = eulerphi(8^n-1)}
(Python)
from sympy import totient
def A366654(n): return totient((1<<3*n)-1) # Chai Wah Wu, Oct 15 2023

Crossrefs

phi(k^n-1): A053287 (k=2), A295500 (k=3), A295501 (k=4), A295502 (k=5), A366623 (k=6), A366635 (k=7), this sequence (k=8), A366663 (k=9), A295503 (k=10), A366685 (k=11), A366711 (k=12).

Cf. A000010, A010705, A024088, A057953, A059890, A274908, A366651, A366652, A366653.

Sequence in context: A185085 A201540 A195229 * A367488 A339300 A296389

Adjacent sequences: A366651 A366652 A366653 * A366655 A366656 A366657

Keyword

nonn

Author

Sean A. Irvine, Oct 15 2023

Status

approved