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 A103046 Numbers n such that 6*10^n + 8*R_n - 1 is prime, where R_n = 11...1 is the repunit (A002275) of length n. 1
 0, 1, 33, 72, 177, 192, 325, 417, 732, 1362, 13947, 14887, 32706, 63954, 64783, 82377 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Also numbers n such that (62*10^n-17)/9 is prime. a(17) > 10^5. - Robert Price, Sep 15 2015 LINKS Table of n, a(n) for n=1..16. Makoto Kamada, Prime numbers of the form 688...887. Index entries for primes involving repunits. FORMULA a(n) = A101539(n-1) + 1 for n>1. MATHEMATICA Do[ If[ PrimeQ[(62*10^n - 17)/9], Print[n]], {n, 0, 10000}] CROSSREFS Cf. A002275, A101539. Sequence in context: A044135 A044516 A015722 * A063868 A184417 A240884 Adjacent sequences: A103043 A103044 A103045 * A103047 A103048 A103049 KEYWORD more,nonn AUTHOR Robert G. Wilson v, Jan 18 2005 EXTENSIONS a(11)-a(12) from Kamada data by Robert Price, Dec 14 2010 a(13) from Erik Branger May 01 2013 by Ray Chandler, Aug 16 2013 Inserted a(1)=0 by Robert Price, Sep 15 2015 a(14)-a(16) from Robert Price, Sep 15 2015 STATUS approved

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Last modified June 22 04:48 EDT 2024. Contains 373565 sequences. (Running on oeis4.)