Numbers of form 3^i*6^j, with i, j >= 0.

Terms

a(0) =1a(1) =3a(2) =6a(3) =9a(4) =18a(5) =27a(6) =36a(7) =54a(8) =81a(9) =108a(10) =162a(11) =216a(12) =243a(13) =324a(14) =486a(15) =648a(16) =729a(17) =972a(18) =1296a(19) =1458a(20) =1944a(21) =2187a(22) =2916a(23) =3888a(24) =4374a(25) =5832a(26) =6561a(27) =7776a(28) =8748a(29) =11664