1,2

Also numbers n such that (7*10^n-43)/9 is prime.

Index entries for primes involving repunits

Do[ If[ PrimeQ[ 7(10^n - 1)/9 - 4], Print[n]], {n, 0, 5000}]

Adjacent sequences: A099417 A099418 A099419 this_sequence A099421 A099422 A099423

Sequence in context: A097937 A141403 A124204 this_sequence A051147 A079741 A000861

nonn

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