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Classical number theory

Source: Iranian third round 2019 Finals Number theory exam problem 2

August 15, 2019
number theory

Problem Statement

Call a polynomial P(x)=anxn+an1xn1+a1x+a0P(x)=a_nx^n+a_{n-1}x^{n-1}+\dots a_1x+a_0 with integer coefficients primitive if and only if gcd(an,an1,a1,a0)=1\gcd(a_n,a_{n-1},\dots a_1,a_0) =1.
a)Let P(x)P(x) be a primitive polynomial with degree less than 13981398 and SS be a set of primes greater than 13981398.Prove that there is a positive integer nn so that P(n)P(n) is not divisible by any prime in SS.
b)Prove that there exist a primitive polynomial P(x)P(x) with degree less than 13981398 so that for any set SS of primes less than 13981398 the polynomial P(x)P(x) is always divisible by product of elements of SS.