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

Terms

a(0) =1a(1) =4a(2) =5a(3) =6a(4) =7a(5) =8a(6) =9a(7) =10a(8) =11a(9) =12a(10) =13a(11) =15a(12) =16a(13) =17a(14) =19a(15) =20a(16) =21a(17) =24a(18) =25a(19) =27a(20) =29a(21) =31a(22) =32a(23) =35a(24) =36a(25) =37a(26) =39a(27) =41a(28) =44a(29) =45