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 A102979 Numbers n such that 3*10^n + 8*R_n - 1 is prime, where R_n = 11...1 is the repunit (A002275) of length n. 1
 0, 1, 6, 10176, 56898 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Also numbers n such that (35*10^n-17)/9 is prime. a(6) > 10^5. - Robert Price, Mar 30 2015 LINKS Makoto Kamada, Prime numbers of the form 388...887. FORMULA a(n) = A101846(n-1) + 1. MATHEMATICA Do[ If[ PrimeQ[(35*10^n - 17)/9], Print[n]], {n, 0, 10000}] CROSSREFS Cf. A002275, A101846. Sequence in context: A172733 A329911 A088021 * A069942 A261823 A146202 Adjacent sequences:  A102976 A102977 A102978 * A102980 A102981 A102982 KEYWORD more,nonn AUTHOR Robert G. Wilson v, Dec 17 2004 EXTENSIONS Additional term 10176 (a PRP) from Serge Batalov, Oct 12 2008 Addition of a(5) from Kamada data by Robert Price, Dec 13 2010 STATUS approved

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Last modified October 30 06:31 EDT 2020. Contains 338077 sequences. (Running on oeis4.)