A144246 Prime numbers of the form 10^k +- 9.

19, 109, 991, 1009, 10009, 99991, 9999991, 1000000009, 1000000000000000009, 10000000000000000000009, 999999999999999999999999999999991, 999999999999999999999999999999999999999999991, 1000000000000000000000000000000000000000000009

Offset: 1

Author

Reikku Kulon, Sep 15 2008

Keywords

• nonn

Comments

This sequence illustrates the base-n representation of numbers having the form n^k +- (n - 1).

Links

• Amiram Eldar, Table of n, a(n) for n = 1..25

Crossrefs

Cf. A000040, A000668, A144231, A144232, A144233, A144234, A144236, A144242, A144245.

Programs

Mathematica

Select[Sort[Flatten[Table[10^n+{9,-9},{n,50}]]],PrimeQ] (* Harvey P. Dale, Jul 22 2016 *)

Extensions

a(13) from Amiram Eldar, Jul 24 2025