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Bouniakowsky Conjecture


The Bouniakowsky conjecture states that an irreducible polynomial f(x) with integer coefficients, positive leading coefficient, and GCD(f(1),f(2),...)=1 takes prime values for infinitely many positive integers x (Bouniakowsky 1857). Irreducibility is over the rational numbers. A polynomial satisfying these conditions and having degree greater than 1 is called a Bouniakowsky polynomial here. The greatest common divisor condition excludes the irreducible polynomial 3x^2-x+2, which is divisible by 2 for every integer x.

For a linear polynomial ax+b, the corresponding hypotheses are a>0 and GCD(a,b)=1. Under these conditions, Dirichlet's theorem gives infinitely many primes. No polynomial with integer coefficients and degree greater than 1 is known to take infinitely many prime values at positive integer inputs (Jones and Zvonkin 2023, Ismailescu and Lee 2025). The assertion that a^2+1 is prime for infinitely many integers a>1 is a special case and one of Landau's problems.

No nonconstant polynomial with integer coefficients can take prime values at every positive integer input. If f(a)=p is prime at a positive integer a, then p divides f(a+tp) for every positive integer t, while |f(a+tp)| eventually exceeds p.

It is also unknown whether every Bouniakowsky polynomial takes even one prime value at a positive integer input. This assertion for every such polynomial is equivalent to the full conjecture, since applying it to f(x+N) for each positive integer N would give prime values at arbitrarily large inputs (Jones and Zvonkin 2023, p. 3). For example, x^(12)+488669 first takes prime values at x=616980, 764400, 933660, ... (Ismailescu and Lee 2025, p. 2; OEIS A122131).


See also

Dirichlet's Theorem, Hardy-Littlewood Conjectures, Landau's Problems, Prime-Generating Polynomial

Portions of this entry contributed by Ed Pegg, Jr. (author's link)

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References

Bouniakowsky, V. "Sur les diviseurs numériques invariables des fonctions rationnelles entières." Mém. Acad. Sci. St. Pétersbourg 6, 305-329, 1857. https://books.google.fr/books?id=wXIhAQAAMAAJ&pg=PA305.Dickson, L. E. History of the Theory of Numbers, Vol. 1: Divisibility and Primality. New York: Dover, pp. 332-333, 2005.Ismailescu, D. and Lee, Y. J. "Polynomially Growing Integer Sequences All Whose Terms Are Composite." 8 Jan 2025. https://arxiv.org/abs/2501.04851.Jones, G. A. and Zvonkin, A. K. "Groups of Prime Degree and the Bateman-Horn Conjecture." Expo. Math. 41, 1-19, 2023. https://doi.org/10.1016/j.exmath.2022.11.002.Ruppert, W. M. "Reducibility of Polynomials f(x,y) Modulo p." 5 Aug 1998. https://arxiv.org/abs/math/9808021.Sloane, N. J. A. Sequence A122131 in "The On-Line Encyclopedia of Integer Sequences."

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Bouniakowsky Conjecture

Cite this as:

Weisstein, Eric W., with contributions by Ed Pegg, Jr.. "Bouniakowsky Conjecture." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/BouniakowskyConjecture.html

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