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Primes of the form identical digits followed by a 9.
2

%I #5 Mar 30 2012 17:30:56

%S 19,29,59,79,89,229,449,11119,22229,44449,111119,444449,11111119,

%T 55555559,555555555559,22222222222229,88888888888889,

%U 11111111111111119,88888888888888889,555555555555555559,55555555555555555555555559

%N Primes of the form identical digits followed by a 9.

%H Vincenzo Librandi, <a href="/A090148/b090148.txt">Table of n, a(n) for n = 1..40</a>

%t Select[ FromDigits /@ Flatten[ Table[ PadLeft[{9}, i, # ] & /@ {1, 2, 3, 4, 5, 6, 7, 8, 9}, {i, 2, 16}], 1], PrimeQ[ # ] &]

%K nonn,base

%O 1,1

%A _Robert G. Wilson v_, Nov 22 2003