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 A090559 Beginning with 2, least number such that concatenation of r copies of a(r), r = 1 to n is prime. 1
 2, 1, 3, 1, 9, 3, 273, 219, 7, 281, 11, 119, 1019, 111, 47, 69, 171, 161, 103, 477, 817, 129, 271, 73, 1867, 381, 507, 113, 2643, 487, 3037, 727, 1109, 1789, 5829, 4937, 767, 12809, 1979, 587, 8417, 1623, 7233, 9079, 6739, 2269, 10251, 8911, 27881, 2691, 5257 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS For n > 1, a(n) is odd and a(n) != 5 mod 10. - Chai Wah Wu, Jun 17 2019 LINKS EXAMPLE 2,211,211333,2113331111,211333111199999 are all prime. CROSSREFS Cf. A090560. Sequence in context: A185176 A198315 A126761 * A186725 A301935 A237978 Adjacent sequences:  A090556 A090557 A090558 * A090560 A090561 A090562 KEYWORD base,more,nonn AUTHOR Amarnath Murthy, Dec 10 2003 EXTENSIONS More terms from Max Alekseyev, Sep 04 2009 a(38)-a(51) from Chai Wah Wu, Jun 17 2019 STATUS approved

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Last modified April 5 03:15 EDT 2020. Contains 333238 sequences. (Running on oeis4.)