A199819 Primes of the form 10^k-9^k.

19, 271, 5217031, 68618940391, 8649148282327007911, 95289871302753755165078396311

Offset: 1

Author

Vincenzo Librandi, Nov 21 2011

Keywords

• nonn

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..9

Crossrefs

Cf. A016189, A062576

Programs

Magma

[ a: n in [0..400] | IsPrime(a) where a is 10^n-9^n ];

Mathematica

Select[10^Range[3000]-9^Range[3000],PrimeQ]

Formula

a(n) = A016189(A062576(n)). - Michel Marcus, Apr 21 2025