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) =2a(1) =4a(2) =5a(3) =7a(4) =9a(5) =10a(6) =11a(7) =13a(8) =15a(9) =17a(10) =19a(11) =21a(12) =22a(13) =25a(14) =27a(15) =29a(16) =30a(17) =31a(18) =35a(19) =37a(20) =39a(21) =41a(22) =44a(23) =45a(24) =46a(25) =49a(26) =51a(27) =54a(28) =55a(29) =57