If k appears so do 2k-2 and 3k-3. (duplicates omitted.)

Terms

a(0) =4a(1) =6a(2) =9a(3) =10a(4) =15a(5) =16a(6) =18a(7) =24a(8) =27a(9) =28a(10) =30a(11) =34a(12) =42a(13) =45a(14) =46a(15) =51a(16) =52a(17) =54a(18) =58a(19) =66a(20) =69a(21) =78a(22) =81a(23) =82a(24) =87a(25) =88a(26) =90a(27) =99a(28) =100a(29) =102