1,2

Also numbers n such that (25*10^n-1)/3 is prime.

Makoto Kamada, Factorizations of 833...33

Index entries for primes involving repunits

Do[ If[ PrimeQ[ 8*10^n + 3*(10^n-1)/9], Print[n]], {n, 0, 10000}]

Sequence in context: A095314 A038948 A019389 this_sequence A080802 A078515 A044449

Adjacent sequences: A056720 A056721 A056722 this_sequence A056724 A056725 A056726

hard,nonn

Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 11 2000

Corrected by Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008