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A366658
a(n) = phi(8^n+1), where phi is Euler's totient function (A000010).
10
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
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
KEYWORD
nonn
AUTHOR
Sean A. Irvine, Oct 15 2023
STATUS
approved