OFFSET
2,2
MATHEMATICA
EulerPhi[Range[2, 25]!-1] (* Paolo Xausa, Oct 21 2023 *)
PROG
(PARI) {a(n) = eulerphi(n!-1)}
(Python)
from math import factorial
from sympy import totient
def A366759(n): return totient(factorial(n)-1) # Chai Wah Wu, Oct 20 2023
CROSSREFS
KEYWORD
nonn
AUTHOR
Sean A. Irvine, Oct 20 2023
STATUS
approved