Fourier coefficients of sextic theta series

This article focuses on the theta series on the 6-fold cover of GL$_2$. We investigate the Fourier coefficients $\tau(r)$ of the theta series, and give partially proven, partially conjectured values for $\tau(\pi)^2$, $\tau(\pi^2)$ and $\tau(\pi^4)$ for prime values $\pi$.