Search: id:A097685
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%I A097685
%S A097685 2,5,6,8,17,50,684,720,1452,1679,3146
%N A097685 Numbers n such that R_n + 8 is prime, where R_n = 11...1 is the repunit 
               (A002275) of length n.
%C A097685 Also numbers n such that (10^n+71)/9 is prime.
%C A097685 Values indicate primes of the form "(n-1) ones followed by a nine". Related 
               to the base 10 repunit primes.
%H A097685 <a href="Sindx_Pri.html#Pri_rep">Index entries for primes involving repunits</
               a>
%t A097685 Do[ If[ PrimeQ[(10^n - 1)/9 + 8], Print[n]], {n, 0, 5000}] (from Robert 
               G. Wilson v Oct 14 2004)
%Y A097685 Equals A056659 + 1. Cf. A004023, A097683, A097684.
%Y A097685 Sequence in context: A045547 A127143 A079256 this_sequence A136369 A007573 
               A143909
%Y A097685 Adjacent sequences: A097682 A097683 A097684 this_sequence A097686 A097687 
               A097688
%K A097685 nonn
%O A097685 1,1
%A A097685 Carl R. White (cyrek(AT)cyreksoft.yorks.com), Aug 19 2004

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