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

1,1

Comments

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

Links

Table of n, a(n) for n=1..6.

Makoto Kamada, Prime numbers of the form 55...559.

Index entries for primes involving repunits

Formula

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

Crossrefs

Cf. A056687 (corresponding k), A099418.

Sequence in context: A235215 A178066 A191947 * A087535 A058931 A092914

Adjacent sequences: A093400 A093401 A093402 * A093404 A093405 A093406

Keyword

nonn

Author

Rick L. Shepherd, Mar 28 2004

Extensions

Edited by Ray Chandler, Feb 27 2012

Status

approved