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 #17 Sep 27 2024 14:26:48
%S 1,2,8,10,20,590,1058
%N Numbers k such that (1/9)*(-1 + 10^k) + k is prime.
%C Some of the larger entries may only correspond to probable primes.
%C a(8) > 6000. - _Tyler NeSmith_, May 09 2021
%C a(8) > 10^5. - _Michael S. Branicky_, Sep 27 2024
%o (PARI) is(n)=ispseudoprime((10^n-1)/9+n) \\ _Charles R Greathouse IV_, Jun 13 2017
%Y Cf. A110369.
%K more,nonn
%O 1,2
%A _Jason Earls_, Jul 25 2005