On the biquadratic Eisenstein series

Biquadratic metaplectic Eisenstein series over the group $\mathrm{SL}_3(\mathbb C)$ are studies, and the “\textrm{sl}(2)-triples” technique for the computation of the Fourier coefficients of these series is used. Also, the biquadratic theta-function over the group $\mathrm{SL}_3(\mathbb C)$ is constructed.