# How about 4, 5, 6?

$\sqrt { ab+56 } -\sqrt { ab-56 } =4$

If all the $$n$$ pairs of positive integers $$(a,b)$$ that satisfy the equation above are

$(a_1 ,b_1) , (a_2, b_2) , \ldots , (a_n, b_n) ,$

submit your answer as $$\displaystyle \sum _{ i=1 }^{ n }{ a_{ i }b_{ i } }$$.

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