Diophantine approximation with one prime, two squares of primes and one $k$-th power of a prime
Alessandro Gambini
Abstract
Let $1<k<14/5$, $λ_1,λ_2,λ_3$ and $λ_4$ be non-zero real numbers, not all of the same sign such that $λ_1/λ_2$ is irrational and let $ω$ be a real number. We prove that the inequality $|λ_1p_1+λ_2p_2^2+λ_3p_3^2+λ_4p_4^k-ω|\le (\max_j p_j)^{-\frac{14-5k}{28k}+\varepsilon}$ has infinitely many solutions in prime variables $p_1,p_2,p_3,p_4$ for any $\varepsilon>0$.
