A216347 Primes of the form n*10^n + 1.

11, 3001, 9000000001, 21000000000000000000001

Offset: 1

Author

Michel Lagneau, Sep 04 2012

Keywords

• nonn

Comments

The corresponding n are in A007647.

a(5) = 363000000….00001 contains 366 digits.

Crossrefs

Cf. A007647.

Programs

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 *)