a(n) = Sum_{k=1..n} phi(gcd(k, n))^n.

Terms

a(0) =1a(1) =2a(2) =10a(3) =19a(4) =1028a(5) =132a(6) =279942a(7) =65798a(8) =10078726a(9) =2097160a(10) =100000000010a(11) =16797702a(13) =156728328204