1,3

Also numbers n such that (10^(n+1)+17)/9 is prime.

Index entries for primes involving repunits

Do[ m = n; If[ primeQ[ 10*(10^n - 1)/9 + 3 ], Print[ n ] ], {n, 1, 1350} ]

Cf. A093011 (corresponding primes).

Sequence in context: A004655 A127101 A124849 this_sequence A020950 A056386 A014425

Adjacent sequences: A056651 A056652 A056653 this_sequence A056655 A056656 A056657

hard,nonn

Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 09 2000

a(10) (only a probable prime) from Rick L. Shepherd (rshepherd2(AT)hotmail.com), Mar 14 2004