a(1) = 3; a(n+1) = a(n)-th nonprime, where nonprimes begin at 0.

Terms

a(0) =3a(1) =4a(2) =6a(3) =9a(4) =14a(5) =21a(6) =30a(7) =42a(8) =57a(9) =77a(10) =102a(11) =133a(12) =171a(13) =217a(14) =274a(15) =341a(16) =422a(17) =518a(18) =632a(19) =766a(20) =922a(21) =1106a(22) =1320a(23) =1565a(24) =1846a(25) =2171a(26) =2541a(27) =2967a(28) =3447a(29) =3996