a(n) = phi(n^6) = n^5*phi(n).

Terms

a(0) =1a(1) =32a(2) =486a(3) =2048a(4) =12500a(5) =15552a(6) =100842a(7) =131072a(8) =354294a(9) =400000a(10) =1610510a(11) =995328a(12) =4455516a(13) =3226944a(14) =6075000a(15) =8388608a(16) =22717712a(17) =11337408a(18) =44569782a(19) =25600000a(20) =49009212a(21) =51536320a(22) =141599546a(23) =63700992a(24) =195312500a(25) =142576512a(26) =258280326a(27) =206524416a(28) =574312172a(29) =194400000