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 A102934 Numbers n such that 10^n + 4*R_n + 3 is prime, where R_n = 11...1 is the repunit (A002275) of length n. 1
 1, 3, 4, 6, 9, 22, 28, 34, 37, 61, 82, 274, 276, 735, 1443, 2215, 2968, 3301, 3883, 3991, 5152, 8032, 8946, 46642, 57691 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Also numbers n such that (13*10^n+23)/9 is prime. a(26) > 10^5. - Robert Price, Feb 19 2015 LINKS Makoto Kamada, Prime numbers of the form 144...447. FORMULA a(n) = A102016(n) + 1. MATHEMATICA Do[ If[ PrimeQ[(13*10^n + 23)/9], Print[n]], {n, 0, 10000}] CROSSREFS Cf. A002275, A102016. Sequence in context: A301657 A241342 A018830 * A191699 A293272 A192286 Adjacent sequences:  A102931 A102932 A102933 * A102935 A102936 A102937 KEYWORD more,nonn AUTHOR Robert G. Wilson v, Dec 16 2004 EXTENSIONS a(24) from Erik Branger May 01 2013 by Ray Chandler, Aug 16 2013 a(25) from Robert Price, Feb 19 2015 STATUS approved

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Last modified April 24 18:03 EDT 2019. Contains 322430 sequences. (Running on oeis4.)