1,2

Also numbers n such that (2*10^(n+1)+43)/9 is prime.

Index entries for primes involving repunits

Do[ If[ PrimeQ[20*(10^n - 1)/9 + 7], Print[n]], {n, 0, 5000}]

Sequence in context: A120413 A161156 A125902 this_sequence A053697 A092346 A166045

Adjacent sequences: A056674 A056675 A056676 this_sequence A056678 A056679 A056680

hard,nonn

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