TITLE: Examples of nice families of irreducible polynomials over Z
QUESTION [6 upvotes]: Hi,
i search for irreducible polynomials over Z which have variable coefficients you can "choose".
Since I found nearly nothing in books or the internet i hope you can help me.
Here 3 examples:
Let g a polynomial over Z with degree smaller then n/2 ,then:
$g* (\prod_{i=1}^n (x-a_i)) -1  $ is irreducible if the a_i are all distinct.
Here you can choose n the coefficients of g and the a_n so its a nice example.
Another one,I found, is from Furtwängler : $x^4 (\prod_{i=1}^{n-4} (x-b_i)) -(-1)^n *(2x+4)  $ where the b_i are strictly increasing.Can you generalize this example ?I think it should work also for some integers other than 2 and 4.
Here is another nice example :
Polynomial with the primes as coefficients irreducible?
I try to find examples where its easy to control zeros modulo p of the some irreducible polynomials and its derivation for another problem.

REPLY [2 votes]: If $m$ and $n$ are odd then $x^5+mx^2+n$ is irreducible over the rationals (as one finds out by reducing it mod 2). 
Michael Filaseta (and various co-authors) has a string of results on families of irreducible polynomials. E.g., Filaseta, Finch and Leidy, T N Shorey's influence in the theory of irreducible polynomials, has results on irreducibility of Laguerre polynomials. Filaseta, Kumchev and Pasechnik, On the irreducibility of a truncated binomial expansion, does what the title says. Filaseta, Luca, Stanica and Underwood, Two diophantine approaches to the irreducibility of certain trinomials, proves that $x^{2p}+bx^p+c$ is irreducible whenever $p$ is an odd prime and $\gcd(p,q^2-1)=1$ for all prime $q$ dividing $181b$. There's more where that came from. If you have access to MathSciNet you might try typing in Filaseta and irreducible.