A032617 Numbers n such that n concatenated with n + 2 is a prime.

1, 7, 9, 27, 37, 45, 49, 51, 55, 61, 69, 75, 105, 109, 115, 117, 121, 151, 159, 181, 187, 195, 201, 211, 217, 225, 247, 271, 277, 285, 289, 291, 301, 309, 319, 321, 331, 337, 339, 357, 361, 367, 381, 391, 399, 405, 417, 421, 427, 429, 435, 439