1,3

Also numbers n such that (5*10^n+13)/9 is prime.

Index entries for primes involving repunits

Do[ If[ PrimeQ[ 5(10^n - 1)/9 + 2], Print[n]], {n, 0, 5000}]

Adjacent sequences: A099414 A099415 A099416 this_sequence A099418 A099419 A099420

Sequence in context: A125869 A059618 A114736 this_sequence A139463 A068922 A032408

nonn

Robert G. Wilson v (rgwv(AT)rgwv.com), Oct 14 2004