a(1) = 7; a(n) is smallest number > a(n-1) such that the juxtaposition a(1)a(2)...a(n) is a prime.

Terms

a(0) =7a(1) =9a(2) =19a(3) =27a(4) =47a(5) =57a(6) =61a(7) =81a(8) =179a(9) =211a(10) =251a(11) =273a(12) =373a(13) =477a(14) =581a(15) =753a(16) =847a(17) =909a(18) =971a(19) =1399a(20) =1623a(21) =1967a(22) =2139a(23) =2629a(24) =2979a(25) =3297a(26) =3393a(27) =3647a(28) =3793a(29) =4281