Numbers of the form 2^i or 3^j.

Terms

a(0) =1a(1) =2a(2) =3a(3) =4a(4) =8a(5) =9a(6) =16a(7) =27a(8) =32a(9) =64a(10) =81a(11) =128a(12) =243a(13) =256a(14) =512a(15) =729a(16) =1024a(17) =2048a(18) =2187a(19) =4096a(20) =6561a(21) =8192a(22) =16384a(23) =19683a(24) =32768a(25) =59049a(26) =65536a(27) =131072a(28) =177147a(29) =262144