A090265 -id:A090265 - cp's OEIS frontend

A090263 Numbers n such that the strings n3n and 3n3 are both prime.

1, 37, 41, 53, 59, 79, 83, 119, 133, 151, 179, 197, 223, 241, 263, 283, 299, 349, 361, 377, 427, 461, 553, 559, 593, 599, 637, 643, 671, 769, 781, 827, 923, 973, 1103, 1117, 1171, 1327, 1333, 1361, 1393, 1399, 1481, 1493, 1537, 1549, 1561, 1619, 1649, 1823

Offset: 1

Amarnath Murthy, Nov 28 2003

			37 is a member as 37337 and 3373 are both prime.

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

Cf. A090262, A090264, A090265.

Select[Range[2000], PrimeQ[FromDigits @ Join[(d = IntegerDigits[#]), {3}, d]] && PrimeQ[FromDigits @ Join[{3}, d, {3}]] &] (* Amiram Eldar, Dec 07 2019 *)

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

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

Original entry on oeis.org

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

Amarnath Murthy, Nov 28 2003

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

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

Cf. A090263, A090264, A090265.

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

A090264 Numbers n such that the strings n7n and 7n7 are both prime.

Original entry on oeis.org

131, 153, 191, 233, 261, 327, 341, 359, 389, 407, 429, 459, 489, 527, 533, 579, 593, 599, 671, 683, 701, 723, 731, 797, 813, 869, 873, 939, 981, 1083, 1097, 1109, 1143, 1187, 1241, 1283, 1317, 1391, 1437, 1451, 1539, 1553, 1871, 1889, 1893, 2049, 2111

Offset: 1

Amarnath Murthy, Nov 28 2003

			131 is a member as 1317131 and 71317 are both prime.

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

Cf. A090262, A090263, A090265.

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

cp's OEIS Frontend

A090263 Numbers n such that the strings n3n and 3n3 are both prime.

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

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Author

Keywords

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Crossrefs

Extensions

A090264 Numbers n such that the strings n7n and 7n7 are both prime.

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