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

1, 5, 85, 155, 383, 6223

Offset

1,2

Comments

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

Links

Table of n, a(n) for n=1..6.

Mathematica

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

Prog

(Magma) [n: n in [0..1000] | IsPrime(13^n+n^13-1)];
(PARI) is(n)=ispseudoprime(13^n+n^13-1) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

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

Sequence in context: A268880 A367192 A048143 * A137083 A198586 A121290

Adjacent sequences: A216417 A216418 A216419 * A216421 A216422 A216423

Keyword

nonn,hard,more

Author

Vincenzo Librandi, Sep 07 2012

Extensions

a(6) from Robert Price, May 24 2014

Status

approved