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

1,1

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

Table of n, a(n) for n=1..8.

Makoto Kamada, Prime numbers of the form 77...773.

Index entries for primes involving repunits

Mathematica

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

Crossrefs

Cf. A056689 (corresponding k), A099420.

Sequence in context: A060883 A162601 A173807 * A189306 A363984 A012810

Adjacent sequences: A093162 A093163 A093164 * A093166 A093167 A093168

Keyword

nonn

Author

Rick L. Shepherd, Mar 26 2004

Status

approved