A089432 Numbers n such that n concatenated with floor(n/2) is prime.

3, 7, 15, 19, 23, 27, 35, 39, 47, 55, 67, 75, 95, 99, 107, 119, 127, 135, 163, 179, 187, 195, 227, 235, 239, 243, 255, 267, 303, 319, 327, 347, 379, 407, 427, 443, 455, 459, 463, 479, 523, 539, 547, 555, 583, 607, 619, 635, 663, 667, 683, 687, 695, 715, 723

Offset: 1

Author

Reinhard Zumkeller, Dec 28 2003

Keywords

• nonn
• base

Comments

All terms are odd.

Crossrefs

Cf. A054211.