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A096498
Prime before n-th repunit.
18
7, 109, 1109, 11093, 111109, 1111091, 11111101, 111111109, 1111111097, 11111111059, 111111111103, 1111111111093, 11111111111053, 111111111111053, 1111111111111039, 11111111111111107, 111111111111111091, 1111111111111111037, 11111111111111111027, 111111111111111111053, 1111111111111111111097
OFFSET
2,1
LINKS
FORMULA
a(n) = A002275(n) - A096870(n) = A096497(n) - A096499(n).
MAPLE
seq(prevprime((10^n-1)/9), n=2..50); # Robert Israel, Nov 13 2017
MATHEMATICA
Table[NextPrime[(10^n - 1)/9, -1], {n, 2, 22}] (* updated by Michael De Vlieger, May 02 2016 *)
PROG
(PARI) a(n) = precprime((10^n-1)/9 - 1); \\ Michel Marcus, May 02 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Jul 09 2004
STATUS
approved