Number of Irreducible Fractions

Find the number of distinct fractions $$\dfrac{a}{b}$$, where both $$a$$ and $$b$$ are integers with $$0\leq a \leq b \leq 50$$ and $$\gcd(a,b)=1$$.

Note: It's acceptable if $$\dfrac{a}{b}$$ equals some integer.

Notation: $$\gcd(\cdot)$$ denotes the greatest common divisor function.

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