a(n) = (8*n + 7)^3.

Terms

a(0) =343a(1) =3375a(2) =12167a(3) =29791a(4) =59319a(5) =103823a(6) =166375a(7) =250047a(8) =357911a(9) =493039a(10) =658503a(11) =857375a(12) =1092727a(13) =1367631a(14) =1685159a(15) =2048383a(16) =2460375a(17) =2924207a(18) =3442951a(19) =4019679a(20) =4657463a(21) =5359375a(22) =6128487a(23) =6967871