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 A102999 Numbers n such that 4*10^n + 8*R_n - 1 is prime, where R_n = 11...1 is the repunit (A002275) of length n. 1
 0, 1, 2, 7, 14, 25, 116, 427, 595, 637, 776, 1706, 16628, 55558 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Also numbers n such that (44*10^n-17)/9 is prime. a(15) > 10^5. - Robert Price, Jun 05 2015 LINKS Makoto Kamada, Prime numbers of the form 488...887. FORMULA a(n) = A101736(n) + 1. MATHEMATICA Do[ If[ PrimeQ[(44*10^n - 17)/9], Print[n]], {n, 0, 10000}] CROSSREFS Cf. A002275, A101736. Sequence in context: A249547 A088207 A194111 * A225277 A014112 A227016 Adjacent sequences:  A102996 A102997 A102998 * A103000 A103001 A103002 KEYWORD more,nonn AUTHOR Robert G. Wilson v, Jan 17 2005 EXTENSIONS Addition of a(13) from Kamada data by Robert Price, Dec 13 2010 a(14) from Robert Price, Jun 05 2015 Prepended a(1) = 0 by Robert Price, Jun 05 2015 STATUS approved

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Last modified September 20 16:46 EDT 2019. Contains 327242 sequences. (Running on oeis4.)