a(n) = least positive integer > a(n-1) and not a(i)*a(j)-1 for 1<=i<j<=n, with initial terms 2,4.

Terms

a(0) =2a(1) =4a(2) =5a(3) =6a(4) =8a(5) =10a(6) =12a(7) =13a(8) =14a(9) =16a(10) =17a(11) =18a(12) =20a(13) =21a(14) =22a(15) =24a(16) =26a(17) =28a(18) =30a(19) =32a(20) =34a(21) =36a(22) =37a(23) =38a(24) =40a(25) =42a(26) =44a(27) =45a(28) =46a(29) =48