OFFSET
1,2
COMMENTS
Note that k must be even.
If it exists, a(13) > 31000. - Hugo Pfoertner, Jun 08 2022
EXAMPLE
For k=2 we obtain f(2) = 3^2 + 5^2 + 7^2 + 11^2 + 13^2 = 373 which is a prime.
MATHEMATICA
Select[Range[0, 1000], PrimeQ[3^# + 5^# + 7^# + 11^# +13^#] &]
PROG
(Python)
from sympy import isprime
from itertools import count, islice
def agen(): yield from (k for k in count(0) if isprime(3**k + 5**k + 7**k + 11**k + 13**k))
print(list(islice(agen(), 9))) # Michael S. Branicky, Jun 07 2022
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Hemjyoti Nath, Jun 07 2022
EXTENSIONS
a(11)-a(12) from Hugo Pfoertner, Jun 07 2022
STATUS
approved