How to solve nonlinear recurrence relation (quadratic)

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Please help me solve this weird recurrence relation. This is not really standard quadratic, so I'm totally confused. I tried with logarithm (but 8 is excess), tried writing this recurrence in one degree up or down... I cannot sleep for days because of this :-( This is what troubles me:$$a_{n+2}a_{n}=a_{n+1}^2+8$$for$$a_1=4$$and$$a_2=6$$ Please just give idea or complete solution (step by step) - I'm desperate!(I don't know how write square, so please edit. Thanks.)