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 A102983 Numbers n such that 4*10^n + R_n + 8 is prime, where R_n = 11...1 is the repunit (A002275) of length n. 1
 2, 5, 77, 206, 1871, 3887, 11582, 20234, 60290 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Also numbers n such that (37*10^n+71)/9 is prime. a(10) > 10^5. - Robert Price, Apr 14 2015 LINKS Makoto Kamada, Prime numbers of the form 411...119. FORMULA a(n) =  A101718(n) + 1. MATHEMATICA Do[ If[ PrimeQ[(37*10^n + 71)/9], Print[n]], {n, 0, 10000}] PROG (MAGMA) [n: n in [0..300] | IsPrime((37*10^n+71) div 9)]; // Vincenzo Librandi, Apr 15 2015 CROSSREFS Cf. A002275, A101718. Sequence in context: A183291 A254405 A216847 * A038583 A082080 A127997 Adjacent sequences:  A102980 A102981 A102982 * A102984 A102985 A102986 KEYWORD more,nonn AUTHOR Robert G. Wilson v, Dec 21 2004 EXTENSIONS Addition of a(7)-a(8) from Kamada data by Robert Price, Dec 13 2010 a(9) from Robert Price, Apr 14 2015 STATUS approved

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Last modified February 23 04:30 EST 2020. Contains 332159 sequences. (Running on oeis4.)