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A366608
a(n) = phi(4^n+1), where phi is Euler's totient function (A000010).
12
1, 4, 16, 48, 256, 800, 3840, 12544, 65536, 186624, 986880, 3345408, 16515072, 52306176, 252645120, 760320000, 4288266240, 13628740608, 64258375680, 218462552064, 1095233372160, 3105655160832, 16510446886912, 56000724240384, 280012271910912, 869940000000000
OFFSET
0,2
LINKS
FORMULA
a(n) = A053285(2*n). - Max Alekseyev, Jan 08 2024
MATHEMATICA
EulerPhi[4^Range[0, 30]+1] (* Paolo Xausa, Oct 14 2023 *)
PROG
(PARI) {a(n) = eulerphi(4^n+1)}
(Python)
from sympy import totient
def A366608(n): return totient((1<<(n<<1))+1) # Chai Wah Wu, Oct 14 2023
KEYWORD
nonn
AUTHOR
Sean A. Irvine, Oct 14 2023
STATUS
approved