A090149 - OEIS

%I #7 Jan 24 2019 15:15:33

%S 11,13,17,19,199,1777,1999,199999,19999999,1777777777,17777777777777,

%T 1333333333333333,1111111111111111111,11111111111111111111111,

%U 199999999999999999999999999,1999999999999999999999999999

%N Primes of the form identical digits preceded by a 1.

%H Vincenzo Librandi, <a href="/A090149/b090149.txt">Table of n, a(n) for n = 1..38</a>

%t Select[FromDigits/@Flatten[Table[PadRight[{1},i,#]&/@{1,3,7,9},{i,2,40}],1],PrimeQ[#]&]

%K nonn,base

%O 1,1

%A _Robert G. Wilson v_, Nov 22 2003

%E Mathematica program modified by _Harvey P. Dale_, Jan 24 2019