

A319217


Integers k such that (13*2^k)^8 + 1 is prime.


1



4, 9, 13, 38, 42, 67, 133, 134, 142, 155, 167, 226, 654, 5787, 6703, 12704, 25969, 70198, 78060, 235304
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OFFSET

1,1


COMMENTS

These numbers are a subset of Generalized Fermat Primes power 8.
All numbers from 1 to 235763 has been checked by LLR, no other primes found.
k is not congruent to 6 mod 25 because otherwise (13*2^k)^8+1 would be divisible by 401.  Bruno Berselli, Sep 21 2018


LINKS



EXAMPLE

4 is a term because (13*2^4)^8+1 = 3503536769037500417 is a prime number.


MATHEMATICA



PROG

(Magma) [n: n in [1..700]  IsPrime((13*2^n)^8+1)]; // Vincenzo Librandi, Sep 21 2018
(PARI) isok(k) = ispseudoprime((13*2^k)^8+1); \\ Altug Alkan, Sep 21 2018


CROSSREFS



KEYWORD

nonn,hard,more


AUTHOR



STATUS

approved



