A class of permutation trinomials over finite fields
Let q > 2 be a prime power and , where . We prove that f is a permutation polynomial of if and only if one of the following occurs: (i) q is even and ; (ii) q ≡ 1 (mod 8) and t² = -2.
Let q > 2 be a prime power and , where . We prove that f is a permutation polynomial of if and only if one of the following occurs: (i) q is even and ; (ii) q ≡ 1 (mod 8) and t² = -2.
In this paper we generalize the method used to prove the Prime Number Theorem to deal with finite fields, and prove the following theorem: where denotes the number of monic irreducible polynomials in with norm .
Hasse showed the existence and computed the Dirichlet density of the set of primes for which the order of is odd; it is . Here we mimic successfully Hasse’s method to compute the density of monic irreducibles in for which the order of is odd. But on the way, we are also led to a new and elementary proof of these densities. More observations are made, and averages are considered, in particular, an average of the ’s as varies through all rational primes.