login
A179117
a(n) = Sum_{d|n} phi(d^phi(d)).
1
1, 2, 7, 10, 501, 20, 100843, 2058, 354301, 4502, 23579476911, 6940, 21505924728445, 3327788, 1366875507, 2147485706, 45798768824157052689, 11691722, 98646963440126439346903, 10240004510, 4203330006607501
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
Cf. A179116, A000010 (phi).
Sequence in context: A151346 A247166 A110739 * A133154 A100020 A241807
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Jul 10 2010
STATUS
approved