Numbers k of the form 2^i*3^j, where i and j >= 1.

Terms

a(0) =6a(1) =12a(2) =18a(3) =24a(4) =36a(5) =48a(6) =54a(7) =72a(8) =96a(9) =108a(10) =144a(11) =162a(12) =192a(13) =216a(14) =288a(15) =324a(16) =384a(17) =432a(18) =486a(19) =576a(20) =648a(21) =768a(22) =864a(23) =972a(24) =1152a(25) =1296a(26) =1458a(27) =1536a(28) =1728a(29) =1944