A216346 Primes of the form k*10^k - 1.

199, 2999, 799999999, 1099999999999, 14999999999999999, 38999999999999999999999999999999999999999, 59999999999999999999999999999999999999999999999999999999999999, 71999999999999999999999999999999999999999999999999999999999999999999999999

Offset

1,1

Comments

The corresponding k are in A059671.

a(9) = 769999999...999999 contains 79 digits.

a(10) = 1169999999...999999 contains 120 digits.

Links

Jason Yuen, Table of n, a(n) for n = 1..13

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

Cf. A059671.

Sequence in context: A052188 A086977 A324628 * A289819 A195523 A163712

Adjacent sequences: A216343 A216344 A216345 * A216347 A216348 A216349

Keyword

nonn

Author

Michel Lagneau, Sep 04 2012

Status

approved