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A093405
Primes of the form 80*R_k + 9, where R_k is the repunit (A002275) of length k.
0
89, 88888888888889, 88888888888888889, 88888888888888888888888888888888889
OFFSET
1,1
COMMENTS
Primes of the form (8*10^k + 1)/9. - Vincenzo Librandi, Jul 17 2012
MATHEMATICA
Select[Table[(8*10^n+1)/9, {n, 1, 200}], PrimeQ] (* Vincenzo Librandi, Jul 17 2012 *)
Select[Table[FromDigits[PadLeft[{9}, n, 8]], {n, 100}], PrimeQ] (* Harvey P. Dale, Dec 15 2023 *)
CROSSREFS
Cf. A056663 (corresponding k).
Sequence in context: A072314 A087538 A087341 * A348166 A221307 A058631
KEYWORD
nonn
AUTHOR
Rick L. Shepherd, Mar 28 2004
STATUS
approved