A093946 Primes of the form 6*10^n - 1.

5, 59, 599, 59999, 599999, 59999999, 59999999999, 59999999999999, 59999999999999999999999, 599999999999999999999999, 59999999999999999999999999999, 59999999999999999999999999999999999

Offset

1,1

Comments

Equivalently, primes of the form 5*10^n + 9*R_n, where R_n is the repunit (A002275) of length n.

Links

Table of n, a(n) for n=1..12.

Makoto Kamada, Prime numbers of the form 599...99.

Index entries for primes involving repunits.

Mathematica

Select[Table[FromDigits[PadRight[{5}, n, 9]], {n, 40}], PrimeQ] (* Harvey P. Dale, Jun 06 2016 *)

Prog

(Magma) [a: n in [0..200] | IsPrime(a) where a is (6*10^n-1)]; // Vincenzo Librandi, May 08 2019

Crossrefs

Cf. A056716 (corresponding n).

Sequence in context: A243219 A113055 A020468 * A249519 A371327 A001059

Adjacent sequences: A093943 A093944 A093945 * A093947 A093948 A093949

Keyword

nonn

Author

Rick L. Shepherd, Apr 17 2004

Status

approved