Is there such a fuction of the form $\displaystyle P(n)$ which returns the $\displaystyle nth$ prime number? The function would be such that:

$\displaystyle P(1) = 2$

$\displaystyle P(2) = 3$

$\displaystyle P(3) = 5$

$\displaystyle P(4) = 7$

$\displaystyle P(5) = 11$

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I think the idea is clear. Is there such a function? Or reasearch on such a function?