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%I #13 Nov 13 2017 19:51:34
%S 7,109,1109,11093,111109,1111091,11111101,111111109,1111111097,
%T 11111111059,111111111103,1111111111093,11111111111053,
%U 111111111111053,1111111111111039,11111111111111107,111111111111111091,1111111111111111037,11111111111111111027,111111111111111111053,1111111111111111111097
%N Prime before n-th repunit.
%H Robert Israel, <a href="/A096498/b096498.txt">Table of n, a(n) for n = 2..999</a>
%F a(n) = A002275(n) - A096870(n) = A096497(n) - A096499(n).
%p seq(prevprime((10^n-1)/9), n=2..50); # _Robert Israel_, Nov 13 2017
%t Table[NextPrime[(10^n - 1)/9, -1], {n, 2, 22}] (* updated by _Michael De Vlieger_, May 02 2016 *)
%o (PARI) a(n) = precprime((10^n-1)/9 - 1); \\ _Michel Marcus_, May 02 2016
%Y Cf. A068693, A002275, A096497.
%K nonn
%O 2,1
%A _Labos Elemer_, Jul 09 2004
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