A093403 Primes of the form 50*R_k + 9, where R_k is the repunit (A002275) of length k.

59, 55555559, 555555555559, 555555555555555559, 55555555555555555555555559, 55555555555555555555555555555559

Offset: 1

Author

Rick L. Shepherd, Mar 28 2004

Keywords

• nonn

Comments

Primes of the form (5*10^k + 31)/9. - Vincenzo Librandi, Nov 17 2010

Links

• Makoto Kamada, Prime numbers of the form 55...559.
• Index entries for primes involving repunits

Crossrefs

Cf. A056687 (corresponding k), A099418.

Formula

a(n) = (50*10^A056687(n) + 31)/9 = (5*10^A099418(n) + 31)/9.

Extensions

Edited by Ray Chandler, Feb 27 2012