A216420 Numbers k such that 13^k + k^13 - 1 is prime.

1, 5, 85, 155, 383, 6223

Offset: 1

Author

Vincenzo Librandi, Sep 07 2012

Keywords

• nonn
• hard
• more

Comments

a(7) > 2*10^5 if it exists. - Robert Price, Jul 07 2014

Crossrefs

Cf. A100357, A215434-A215437, A215439-A215445, A216375.

Programs

Magma

[n: n in [0..1000] | IsPrime(13^n+n^13-1)];

Mathematica

Select[Range[0, 5000], PrimeQ[13^# + #^13 - 1] &]

PARI

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

Extensions

a(6) from Robert Price, May 24 2014