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 $\pi$.