1,1

Not proved, only Fermat and Lucas PRPs. Next term is greater than 12000. Concerning primes of the form n * 10^n + n + 1, only n=42 yields one for all n up to 7700.

Table of n, a(n) for n=1..4.

(PARI) is(n)=ispseudoprime(n*10^n+n-1) \\ Charles R Greathouse IV, Jun 13 2017

Sequence in context: A234816 A245868 A251461 * A235071 A235064 A070835

Adjacent sequences: A110282 A110283 A110284 * A110286 A110287 A110288

more,nonn

Jason Earls (zevi_35711(AT)yahoo.com), Sep 07 2005

approved