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

Terms

a(0) =2a(1) =4a(2) =5a(3) =6a(4) =7a(5) =8a(6) =9a(7) =11a(8) =13a(9) =15a(10) =17a(11) =19a(12) =21a(13) =23a(14) =25a(15) =27a(16) =29a(17) =31a(18) =33a(19) =35a(20) =39a(21) =41a(22) =43a(23) =45a(24) =49a(25) =51a(26) =53a(27) =55a(28) =59a(29) =61