OFFSET
1,1
COMMENTS
The corresponding n are in A059671.
a(9) = 769999999….999999 contains 79 digits.
a(10) = 1169999999….999999 contains 120 digits.
MATHEMATICA
lst={}; Do[ p=n*10^n- 1; If[PrimeQ[p], AppendTo[lst, p]], {n, 0, 60}]; lst
Select[Table[n*10^n-1, {n, 100}], PrimeQ] (* Harvey P. Dale, Sep 17 2023 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Lagneau, Sep 04 2012
STATUS
approved