%I #6 May 09 2021 08:09:25
%S 1,2,7,10,501,20,100843,2058,354301,4502,23579476911,6940,
%T 21505924728445,3327788,1366875507,2147485706,45798768824157052689,
%U 11691722,98646963440126439346903,10240004510,4203330006607501
%N a(n) = Sum_{d|n} phi(d^phi(d)).
%C phi(n) = A000010(n) is the Euler totient function of n.
%F Equals one-half the logarithmic derivative of A179116.
%F 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
%o (PARI) {a(n)=sumdiv(n,d,eulerphi(d^eulerphi(d)))}
%Y Cf. A179116, A000010 (phi).
%K nonn
%O 1,2
%A _Paul D. Hanna_, Jul 10 2010