The composite numbers: numbers n of the form x*y for x > 1 and y > 1.

Terms

a(0) =4a(1) =6a(2) =8a(3) =9a(4) =10a(5) =12a(6) =14a(7) =15a(8) =16a(9) =18a(10) =20a(11) =21a(12) =22a(13) =24a(14) =25a(15) =26a(16) =27a(17) =28a(18) =30a(19) =32a(20) =33a(21) =34a(22) =35a(23) =36a(24) =38a(25) =39a(26) =40a(27) =42a(28) =44a(29) =45