OFFSET
1,6
FORMULA
a(n) = Product_{d|n, d < n} phi(d)^phi(n/d).
MATHEMATICA
Table[Product[EulerPhi[GCD[n, k]], {k, 1, n - 1}], {n, 1, 50}]
PROG
(PARI) a(n) = prod(k=1, n-1, eulerphi(gcd(n, k))); \\ Michel Marcus, Nov 28 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Nov 28 2021
STATUS
approved