a(n) = (9*n + 7)^3.

Terms

a(0) =343a(1) =4096a(2) =15625a(3) =39304a(4) =79507a(5) =140608a(6) =226981a(7) =343000a(8) =493039a(9) =681472a(10) =912673a(11) =1191016a(12) =1520875a(13) =1906624a(14) =2352637a(15) =2863288a(16) =3442951a(17) =4096000a(18) =4826809a(19) =5639752a(20) =6539203a(21) =7529536a(22) =8615125