OFFSET
1,1
COMMENTS
Primes of the form 2 + (10^k - 1)/9, k > 0. - Vincenzo Librandi, Dec 13 2011
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..9
Makoto Kamada, Prime numbers of the form 11...113.
MATHEMATICA
Select[Table[(((10^n-1)/ 9)+2), {n, 1, 900}], PrimeQ] (* Vincenzo Librandi, Dec 13 2011 *)
PROG
(Magma) [a: n in [1..100] | IsPrime(a) where a is ((10^n-1) div 9)+2 ]; // Vincenzo Librandi, Dec 13 2011
CROSSREFS
KEYWORD
nonn
AUTHOR
Rick L. Shepherd, Mar 14 2004
STATUS
approved