Numbers k such that the concatenations of k and 123456789 in both orders are prime.

Terms

a(0) =217a(1) =409a(2) =629a(3) =653a(4) =779a(5) =871a(6) =881a(7) =1091a(8) =1463a(9) =1489a(10) =1913a(11) =1993a(12) =2039a(13) =2729a(14) =2881a(15) =3397a(16) =3649a(17) =3677a(18) =3751a(19) =3961a(20) =4073a(21) =4321a(22) =4843a(23) =4961a(24) =5039a(25) =5507a(26) =5609a(27) =5683a(28) =5849a(29) =5941