OFFSET
1,1
COMMENTS
The corresponding n are in A007647.
a(5) = 363000000….00001 contains 366 digits.
MATHEMATICA
lst={}; Do[ p=n*10^n+ 1; If[PrimeQ[p], AppendTo[lst, p]], {n, 0, 21}]; lst
Select[Table[n*10^n+1, {n, 40}], PrimeQ] (* Harvey P. Dale, Jul 18 2020 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Lagneau, Sep 04 2012
STATUS
approved