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%I #9 Dec 24 2024 22:14:18
%S 168,760,2154,9172
%N Numbers k such that k*10^k + k - 1 is prime.
%C Not proved, only Fermat and Lucas PRPs. Next term is greater than 12000. Concerning primes of the form k * 10^k + k + 1, only k = 42 yields one for all k up to 7700.
%C Next term is greater than 72000. - _Michael S. Branicky_, Dec 24 2024
%o (PARI) is(n)=ispseudoprime(n*10^n+n-1) \\ _Charles R Greathouse IV_, Jun 13 2017
%K more,nonn
%O 1,1
%A _Jason Earls_, Sep 07 2005