a(n) = least positive integer > a(n-1) and not a(i)*a(j)-1 for 1<=i<j<=n, with initial terms 1,3.

Terms

a(0) =1a(1) =3a(2) =4a(3) =5a(4) =6a(5) =7a(6) =8a(7) =9a(8) =10a(9) =12a(10) =13a(11) =15a(12) =16a(13) =18a(14) =21a(15) =22a(16) =24a(17) =25a(18) =28a(19) =30a(20) =32a(21) =33a(22) =36a(23) =37a(24) =40a(25) =42a(26) =43a(27) =45a(28) =46a(29) =48