A093402 Primes of the form 40*R_k + 9, where R_k is the repunit (A002275) of length k.

449, 44449, 444449, 444444444444444444444444444444444444444444444449, 444444444444444444444444444444444444444444444444444444444444444444444444444444444444444444444444444444444449

Offset

1,1

Comments

Primes of the form (4*10^k + 41)/9. - Vincenzo Librandi, Nov 16 2010

Links

Table of n, a(n) for n=1..5.

Makoto Kamada, Prime numbers of the form 44...449.

Index entries for primes involving repunits

Mathematica

Select[Table[FromDigits[PadLeft[{9}, n, 4]], {n, 120}], PrimeQ] (* Harvey P. Dale, May 21 2011 *)

Crossrefs

Cf. A056683 (corresponding k).

Sequence in context: A036945 A201182 A012169 * A012062 A339978 A351947

Adjacent sequences: A093399 A093400 A093401 * A093403 A093404 A093405

Keyword

nonn

Author

Rick L. Shepherd, Mar 28 2004

Status

approved