login
A217355
Numbers k such that 8^k + 5 is prime.
4
1, 47, 91, 64655
OFFSET
1,2
COMMENTS
All terms are 1/3 of the terms of A059242 that are multiples of 3.
No more terms <= 10^5. - Tyler NeSmith
MATHEMATICA
Select[Range[1000], PrimeQ[8^# + 5] &]
PROG
(Magma) [n: n in [0..1000] | IsPrime(8^n + 5)];
(PARI) is(n)=ispseudoprime(8^n+5) \\ Charles R Greathouse IV, Feb 20 2017
CROSSREFS
Sequence in context: A272879 A139968 A132451 * A004943 A004963 A061153
KEYWORD
nonn,hard,more
AUTHOR
Vincenzo Librandi, Oct 02 2012
EXTENSIONS
a(4) from Tyler NeSmith, Jan 19 2021
STATUS
approved