# Special series

Calculus Level 4

$\large 1+\frac { 1 }{ 5 } +\frac { 1\times 3 }{ 5\times 10 } +\frac { 1\times 3\times 5 }{ 5\times 10\times 15 } + \ldots$

If the square of the series above equals to $${\dfrac ab}$$ for coprime positive integers $$a,b$$, what is the value of $$a+b$$.

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