1,2

Also numbers n such that (68*10^n+31)/9 is prime.

Makoto Kamada, Factorizations of 755...559.

Index entries for primes involving repunits.

Do[ If[ PrimeQ[(68*10^n + 31)/9], Print[n]], {n, 0, 10000}]

Sequence in context: A072320 A162603 A053970 this_sequence A157723 A142730 A024044

Adjacent sequences: A103059 A103060 A103061 this_sequence A103063 A103064 A103065

more,nonn

Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 19 2005