( q t + 1 1 − t ) ( s 4 t 4 + q s 2 t 4 + s 2 t 2 + q t 2 + 1 ) {\displaystyle \left({\frac {{q}{t}+1}{1-t}}\right)(s^{4}t^{4}+{q}s^{2}t^{4}+s^{2}t^{2}+{q}t^{2}+1)}
