n*phi(n)*phi(phi(n)) is a fourth power.

Terms

a(0) =1a(1) =32a(2) =512a(3) =3888a(4) =8192a(5) =25000a(6) =62208a(7) =131072a(8) =314928a(9) =400000a(10) =759375a(11) =995328a(12) =2097152a(13) =2839714a(14) =3037500