OFFSET
1,2
COMMENTS
phi(n) = A000010(n) is the Euler totient function of n.
FORMULA
Equals one-half the logarithmic derivative of A179116.
a(n) = Sum_{k=1..n} phi(gcd(n,k)^phi(gcd(n,k)))/phi(n/gcd(n,k)). - Richard L. Ollerton, May 09 2021
PROG
(PARI) {a(n)=sumdiv(n, d, eulerphi(d^eulerphi(d)))}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Jul 10 2010
STATUS
approved