A110680 Numbers n such that the string 4444n is prime.

9, 21, 43, 49, 61, 63, 69, 73, 87, 109, 127, 147, 159, 169, 171, 201, 207, 213, 217, 229, 241, 261, 289, 291, 331, 339, 357, 369, 381, 397, 409, 469, 471, 483, 487, 507, 519, 549, 591, 607, 621, 639, 663, 669, 697, 703, 711, 717, 729, 747