# Floored by Primes

Algebra Level 5

For how many positive integers $$N$$ is $$\left \lfloor \frac {N^2}{5} \right \rfloor$$ a prime?

Details and assumptions

The function $$\lfloor x \rfloor: \mathbb{R} \rightarrow \mathbb{Z}$$ refers to the greatest integer smaller than or equal to $$x$$. For example $$\lfloor 2.3 \rfloor = 2$$ and $$\lfloor -5 \rfloor = -5$$.

0 and 1 are not primes.

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