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A216425
Numbers k such that 6^k + k^6 - 1 is prime.
1
12, 24, 72, 13404, 179964
OFFSET
1,1
COMMENTS
a(6) > 2*10^5. - Robert Price, Apr 14 2014
a(1)-a(5) are multiples of 12. - Robert Price, Apr 14 2014
MATHEMATICA
Select[Range[0, 10000], PrimeQ[6^# + #^6 - 1] &]
PROG
(Magma) [n: n in [0..1000] | IsPrime(6^n+n^6-1)];
(PARI) is(n)=ispseudoprime(6^n+n^6-1) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Vincenzo Librandi, Sep 07 2012
EXTENSIONS
a(4)-a(5) from Robert Price, Apr 14 2014
STATUS
approved