A216619 Numbers k such that 10^k + k^10 - 1 is prime.

2, 8, 1592, 2380

Offset: 1

Author

Vincenzo Librandi, Sep 11 2012

Keywords

• nonn
• hard
• more

Comments

Next term > 10^4.

a(5) > 10^5. - Robert Price, Oct 08 2015

Crossrefs

Cf. A100357, A215434-A215446, A216375.

Programs

Mathematica

Select[Range[0, 5000], PrimeQ[10^# + #^10 - 1] &]

PARI

is(n)=ispseudoprime(10^n+n^10-1) \\ Charles R Greathouse IV, Jun 13 2017