a(n) = Sum_{p|n, p prime} (n/p)^lcm(p,n/p).

Terms

a(0) =0a(1) =1a(2) =1a(3) =4a(4) =1a(5) =793a(6) =1a(7) =256a(8) =27a(9) =9766649a(10) =1a(11) =16823872a(12) =1a(13) =678223089233a(14) =30531927032a(15) =16777216a(16) =1a(18) =1a(22) =1a(24) =3125a(26) =387420489