A093404 Primes of the form 70*R_k + 9, where R_k is the repunit (A002275) of length k.

79, 777777777777777777777777777777777777777777777777777777777777777779, 77777777777777777777777777777777777777777777777777777777777777777777777777777777777779, 777777777777777777777777777777777777777777777777777777777777777777777777777777777777777779

Offset: 1

Author

Rick L. Shepherd, Mar 28 2004

Keywords

• nonn

Comments

Primes of the form (7*10^k + 11)/9. - Vincenzo Librandi, Nov 16 2010

Links

• Makoto Kamada, Prime numbers of the form 77...779.
• Index entries for primes involving repunits

Crossrefs

Cf. A002275, A056693 (corresponding k), A098089.

Programs

Mathematica

Select[Table[FromDigits[PadLeft[{9},n,7]],{n,100}],PrimeQ] (* Harvey P. Dale, May 09 2012 *)