Paper 2007/301

On Asymptotic Behavior of the Ratio Between the Numbers of Binary Primitive and Irreducible Polynomials

Yuri Borissov, Moon Ho Lee, and Svetla Nikova

Abstract

In this paper we study the ratio $\theta(n) = \frac{\lambda_2(n)}{\psi_2(n)}$, where ${\lambda_2(n)}$ is the number of primitive polynomials and ${\psi_2(n)}$ is the number of irreducible polynomials in $GF(2)[x]$ of degree $n$. %and $2n$, for an arbitrary odd number $n$. Let $n=\prod_{i=1}^{\ell} p_i^{r_i}$ be the prime factorization of $n$, where $p_i$ are odd primes. We show that $\theta(n)$ tends to 1 and $\theta(2n)$ is asymptotically not less than 2/3 when $r_i$ are fixed and $p_i$ tend to infinity. We also, describe an infinite series of values $n_{s}$ such that $\theta(n_{s})$ is strictly less than $\frac{1}{2}$.