On the non-quadraticity of values of the q-exponential function and related q-series

We investigate arithmetic properties of values of the entire function $$ F(z)=F_q(z;lambda)=sum_{n=0}^inftyfrac{z^n}{prod_{j=1}^n(q^j-lambda)}, qquad |q|>1, quad lambda otin q^{mathbb Z_{>0}}, $$ that includes as special cases the Tschakaloff function ($lambda=0$) and the $q$-exponential function ($lambda=1$). In particular, we prove the non-quadraticity of the numbers $F_q(alpha;lambda)$ for integral $q$, rational $lambda$ and $alpha otin-lambda q^{mathbb Z_{>0}}$, $alpha e0$.