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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
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.
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
KEYWORD
nonn
AUTHOR
Rick L. Shepherd, Apr 17 2004
STATUS
approved