a(n) = Sum_{k=1..n} n^rad(k).

Terms

a(0) =1a(1) =6a(2) =39a(3) =100a(4) =3305a(5) =54726a(6) =958447a(7) =2392776a(8) =5375169a(9) =10011102310a(10) =311270518031a(11) =804967791420