A090265 Numbers n such that the strings n9n and 9n9 are both prime.

1, 19, 41, 43, 47, 61, 67, 71, 73, 83, 107, 149, 211, 217, 221, 269, 277, 319, 437, 443, 523, 547, 553, 607, 619, 647, 679, 697, 817, 863, 877, 899, 1171, 1283, 1297, 1379, 1481, 1547, 1621, 1853, 1867, 1967, 1993, 1997, 2021, 2053, 2107, 2357, 2359, 2393