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 A090264 Numbers n such that the strings n7n and 7n7 are both prime. 4
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Daniel Starodubtsev, Table of n, a(n) for n = 1..10000 EXAMPLE 131 is a member as 1317131 and 71317 are both prime. CROSSREFS Cf. A090262, A090263, A090265. Sequence in context: A164294 A155924 A270237 * A132254 A087832 A335271 Adjacent sequences:  A090261 A090262 A090263 * A090265 A090266 A090267 KEYWORD base,nonn AUTHOR Amarnath Murthy, Nov 28 2003 EXTENSIONS More terms from mohammed bouayoun (bouyao(AT)wanadoo.fr), Feb 02 2004 STATUS approved

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Last modified December 1 12:50 EST 2020. Contains 338833 sequences. (Running on oeis4.)