# Sum of Weird Fractions

Algebra Level 3

$\large \frac{1}{4}+\frac{3}{8}+\frac{5}{16}+\frac{7}{32}+\dots$

If the value of the above series can be expressed as $$\frac{a}{b}$$ where $$a$$ and $$b$$ are coprime positive integers. Find $$a-b$$.

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