A216425 Numbers k such that 6^k + k^6 - 1 is prime.

12, 24, 72, 13404, 179964

Offset: 1

Author

Vincenzo Librandi, Sep 07 2012

Keywords

• nonn
• hard
• more

Comments

a(6) > 2*10^5. - Robert Price, Apr 14 2014

a(1)-a(5) are multiples of 12. - Robert Price, Apr 14 2014

Crossrefs

Cf. A100357, A215434-A215446, A216375.

Programs

Magma

[n: n in [0..1000] | IsPrime(6^n+n^6-1)];

Mathematica

Select[Range[0, 10000], PrimeQ[6^# + #^6 - 1] &]

PARI

is(n)=ispseudoprime(6^n+n^6-1) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(4)-a(5) from Robert Price, Apr 14 2014