I'm trying to prove the irreducibility over the rationals of the polynomial defined by
$$f(x)=(n+1)+nx+(n-1)x^2\ldots+x^n$$
for all $n\in\mathbb{N}$. Computationally, I've verified it is always irreducible up to $n=4096$. It seems like it should be a polynomial that has been studied before, so I'm wondering if anyone recognizes it or if there's a simple trick I'm just missing. Any help would be appreciated!