The OEIS is supported by the many generous donors to the OEIS Foundation.
Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.
Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.
%I #3 Oct 01 2013 17:58:00
%S 109,1009,10009,1000099,1000009999,1000000999999,10000000999,
%T 1000000009,1000000000999999999,10000000000099,100000000000099,
%U 100000000000009999,10000000000000099,100000000000000099,1000000000000000009
%N First prime in primes of the form 10^n + 10^(n-k) - 1.
%o (PARI) f(n,z) = for(x=z,n,y=10^x+10^(x-z)-1;if(ispseudoprime(y),print1(y",")))
%K nonn
%O 1,1
%A _Cino Hilliard_, Jul 28 2004