1,1

Also numbers n such that 10^(n+1) - 9 is a prime.

Index entries for primes involving repunits

Do[ If[ PrimeQ[90*(10^n - 1)/9 + 1], Print[n]], {n, 0, 7000}]

Sequence in context: A046847 A121069 A100838 this_sequence A045662 A084324 A066220

Adjacent sequences: A056693 A056694 A056695 this_sequence A056697 A056698 A056699

hard,nonn

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