We have the following variant of harmonic oscillators.
$$ \left\{ \begin{array}{**lr**} T = a + a^\dagger\\ a | n \rangle = \sqrt{[n]} |n-1 \rangle \\ a^\dagger |n\rangle = \sqrt{[n+1]} |n+1\rangle\\ [n] = \frac{1}{2}(\alpha\frac{1-q_1^n}{1-q_1} + \beta\frac{1-q_2^n}{1-q_2}) \end{array} \right. $$
where $0<q_1,q_2<1$.
My question is how to calculate the quantity $$ \langle n \mid T^k \mid m\rangle $$
For the special case $\alpha = \beta =1, q_1 = q_2 = q$, this system becomes a q-deformed harmonic oscillator, which can be solved analytically.