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A093946 Primes of the form 6*10^n - 1. 0
5, 59, 599, 59999, 599999, 59999999, 59999999999, 59999999999999, 59999999999999999999999, 599999999999999999999999, 59999999999999999999999999999, 59999999999999999999999999999999999 (list; graph; refs; listen; history; text; internal format)
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 A001059 A290702

Adjacent sequences:  A093943 A093944 A093945 * A093947 A093948 A093949

KEYWORD

nonn

AUTHOR

Rick L. Shepherd, Apr 17 2004

STATUS

approved

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Last modified October 23 23:51 EDT 2019. Contains 328379 sequences. (Running on oeis4.)