a(1) = 5; a(n) is smallest number >= a(n-1) such that the juxtaposition a(1)a(2)...a(n) is a prime.

Terms

a(0) =5a(1) =9a(2) =9a(3) =21a(4) =53a(5) =67a(6) =71a(7) =87a(8) =87a(9) =91a(10) =117a(11) =161a(12) =187a(13) =213a(14) =363a(15) =419a(16) =501a(17) =537a(18) =543a(19) =739a(20) =879a(21) =1101a(22) =1329a(23) =1391a(24) =1641a(25) =1939a(26) =2093a(27) =2109a(28) =2331a(29) =2557