On Waring-Goldbach problem for two squares, three biquadratics, one quintic and one septic

Linji Long, Jinjiang Li, Min Zhang

In this paper, it is proved that every sufficiently large odd integer $n$ can be represented as \begin{equation*} n=p_1^2+p_2^2+p_3^4+p_4^4+p_5^4+p_6^5+p_7^7, \end{equation*} where…