OFFSET
2,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 2..138 (terms 2..102 from Robert G. Wilson v)
MAPLE
a:= n-> numtheory[phi](n^n-1):
seq(a(n), n=2..20); # Alois P. Heinz, Oct 26 2023
MATHEMATICA
Array[EulerPhi[#^# - 1] &, 18, 2] (* Michael De Vlieger, Oct 24 2023 *)
PROG
(PARI) a(n) = eulerphi(n^n-1);
CROSSREFS
KEYWORD
nonn
AUTHOR
Sean A. Irvine, Oct 24 2023
STATUS
approved