A093400 Primes of the form 10*R_k + 9, where R_k is the repunit (A002275) of length k.

19, 11119, 111119, 11111119, 11111111111111119, 11111111111111111111111111111111111111111111111119

Offset: 1

Author

Rick L. Shepherd, Mar 28 2004

Keywords

• nonn

Comments

The next term has 684 digits. - Harvey P. Dale, Dec 11 2013

Links

• Makoto Kamada, Prime numbers of the form 11...119.
• Index entries for primes involving repunits

Crossrefs

Cf. A056659 (corresponding k and count of digits 1 in a(n)).

Programs

Mathematica

Select[Table[FromDigits[PadLeft[{9},n,1]],{n,1000}],PrimeQ] (* Harvey P. Dale, Dec 11 2013 *)