Exactly 6 digits from {1,2,3,4,5,6,7,8,9} can precede a(n) to form a prime.

Terms

a(0) =3a(1) =57a(2) =297a(3) =2189a(4) =25697a(5) =76721a(6) =123747a(7) =124443a(8) =132653a(9) =218207a(10) =244099a(11) =261023a(12) =267787a(13) =297059a(14) =304389a(15) =346623a(16) =366989a(17) =411971a(18) =462751a(19) =551057a(20) =596897a(21) =643181a(22) =647193a(23) =665967a(24) =671573a(25) =688143a(26) =701207a(27) =742197a(28) =748563a(29) =867003