a(n) = Sum_{d|n} phi(d^phi(d)).

Terms

a(0) =1a(1) =2a(2) =7a(3) =10a(4) =501a(5) =20a(6) =100843a(7) =2058a(8) =354301a(9) =4502a(10) =23579476911a(11) =6940a(13) =3327788a(14) =1366875507a(15) =2147485706a(17) =11691722a(19) =10240004510