If x and y are terms, so is x*y + 9.

Terms

a(0) =2a(1) =13a(2) =35a(3) =79a(4) =167a(5) =178a(6) =343a(7) =365a(8) =464a(9) =695a(10) =739a(11) =937a(12) =1036a(13) =1234a(14) =1399a(15) =1487a(16) =1883a(17) =2081a(18) =2180a(19) =2323a(20) =2477a(21) =2774a(22) =2807a(23) =2983a(24) =3775a(25) =4171a(26) =4369a(27) =4468a(28) =4655a(29) =4754