5-idempotent numbers.

Terms

a(0) =1a(1) =30a(2) =525a(3) =7000a(4) =78750a(5) =787500a(6) =7218750a(7) =61875000a(8) =502734375a(9) =3910156250a(10) =29326171875a(11) =213281250000