login
Primes of the form identical digits preceded by a 6.
2

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

%S 61,67,677,67777,611111,61111111,67777777777,67777777777777,

%T 61111111111111111111111111,67777777777777777777777777,

%U 61111111111111111111111111111111

%N Primes of the form identical digits preceded by a 6.

%H Vincenzo Librandi, <a href="/A090154/b090154.txt">Table of n, a(n) for n = 1..23</a>

%t Select[ FromDigits /@ Flatten[ Table[ PadRight[{6}, i, # ] & /@ {1, 2, 3, 4, 5, 6, 7, 8, 9}, {i, 2, 100}], 1], PrimeQ[ # ] &]

%K nonn,base

%O 1,1

%A _Robert G. Wilson v_, Nov 22 2003