OFFSET
1,1
COMMENTS
Numbers k such that A363796(k) = -1.
Includes k = (q^2-1)/2 + j*(q^2-q) for odd primes q and nonnegative integers j such that q^k + 2*k is not prime, since for primes p <> q we have q | p^k + 2*k. Conjecture: all terms are of this form.
EXAMPLE
a(3) = 22 is a term because 3 | p^22 + 2*22 for all primes p <> 3, while 3^22 + 2*22 = 31381059653 = 59 * 2447 * 217361 is not prime.
MAPLE
# Run Maple program for A363796. Then:
select(k -> V[k]=-1, [$1..400]);
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert Israel, Jun 23 2023
STATUS
approved