1,2

Also numbers n such that (5*10^(n+1)+13)/9 is prime.

Index entries for primes involving repunits

Do[ If[ PrimeQ[50*(10^n - 1)/9 + 7], Print[n]], {n, 0, 5000}]

Adjacent sequences: A056683 A056684 A056685 this_sequence A056687 A056688 A056689

Sequence in context: A023672 A023567 A076027 this_sequence A079962 A124502 A026746

hard,nonn

Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 10 2000