A093165 Primes of the form 70*R_k + 3, where R_k is the repunit (A002275) of length k.

3, 73, 773, 77773, 777777773, 777777777773, 777777777777773, 777777777777777777773

Offset: 1

Author

Rick L. Shepherd, Mar 26 2004

Keywords

• nonn

Comments

Primes of the form (7*10^k - 43)/9. - Vincenzo Librandi, Nov 16 2010

The next term, a(9), has 264 digits. - Harvey P. Dale, Jul 19 2012

Links

• Makoto Kamada, Prime numbers of the form 77...773.
• Index entries for primes involving repunits

Crossrefs

Cf. A056689 (corresponding k), A099420.

Programs

Mathematica

Select[Table[FromDigits[PadLeft[{3},n,7]],{n,500}],PrimeQ] (* Harvey P. Dale, Jul 19 2012 *)