1,1

Also numbers n such that (5*10^(n+1)-41)/9 is prime.

Index entries for primes involving repunits

Do[ If[ PrimeQ[50*(10^n - 1)/9 + 1], Print[n]], {n, 15000}]

Sequence in context: A041262 A041607 A042097 this_sequence A042731 A087304 A121808

Adjacent sequences: A056681 A056682 A056683 this_sequence A056685 A056686 A056687

hard,nonn,bref

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