a(1) = 6; a(n) is smallest number > a(n-1) such that the juxtaposition a(1)a(2)...a(n) is a prime.

Terms

a(0) =6a(1) =7a(2) =19a(3) =21a(4) =23a(5) =27a(6) =57a(7) =183a(8) =207a(9) =231a(10) =247a(11) =267a(12) =399a(13) =417a(14) =441a(15) =459a(16) =569a(17) =603a(18) =693a(19) =847a(20) =933a(21) =1107a(22) =1149a(23) =1197a(24) =1251a(25) =1581a(26) =1619a(27) =2061a(28) =2137a(29) =2139