1,2

Also numbers n such that (10^(n+1)+71)/9 is prime.

Index entries for primes involving repunits

Do[ If[ PrimeQ[10*(10^n - 1)/9 + 9], Print[n]], {n, 5000}]

See A097685 for another version.

Sequence in context: A106170 A085195 A107289 this_sequence A049896 A029520 A123368

Adjacent sequences: A056656 A056657 A056658 this_sequence A056660 A056661 A056662

hard,nonn

Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 09 2000