A090262 Numbers n such that the strings n1n and 1n1 are both prime.

3, 9, 17, 29, 47, 51, 81, 87, 113, 117, 131, 141, 201, 239, 291, 333, 359, 371, 393, 443, 459, 489, 509, 539, 573, 623, 663, 681, 749, 819, 821, 873, 903, 947, 1071, 1077, 1161, 1269, 1533, 1563, 1589, 1613, 1637, 1673, 1767, 1773, 1821, 1841, 1883, 1959, 1977

Offset: 1

Author

Amarnath Murthy, Nov 28 2003

Keywords

• base
• nonn

Examples

			9 is a member as 919 and 191 are both prime.
		

Links

• Daniel Starodubtsev, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A090263, A090264, A090265.

Extensions

More terms from mohammed bouayoun (bouyao(AT)wanadoo.fr), Feb 02 2004