A090262 -id:A090262 - 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

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

A090265 Numbers n such that the strings n9n and 9n9 are both prime.

Original entry on oeis.org

1, 19, 41, 43, 47, 61, 67, 71, 73, 83, 107, 149, 211, 217, 221, 269, 277, 319, 437, 443, 523, 547, 553, 607, 619, 647, 679, 697, 817, 863, 877, 899, 1171, 1283, 1297, 1379, 1481, 1547, 1621, 1853, 1867, 1967, 1993, 1997, 2021, 2053, 2107, 2357, 2359, 2393

Offset: 1

Amarnath Murthy, Nov 28 2003

			41 is a member as 41941 and 9419 are both prime.

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Cf. A090262, A090263, A090264.

n9Q[n_]:=Module[{idn=IntegerDigits[n]},AllTrue[{FromDigits[Join[idn,{9}, idn]],FromDigits[ Join[{9},idn,{9}]]},PrimeQ]]; Select[Range[2500],n9Q] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Feb 01 2016 *)

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

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Extensions

A090265 Numbers n such that the strings n9n and 9n9 are both prime.

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Mathematica

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