# Can you Identify?

Calculus Level 4

$\sum_{n = 1}^{49} \frac{1}{\sqrt{n + \sqrt{(n - 1)(n + 1)}}} = a + b\sqrt{c}$

$$a, b, c$$ are positive integers, and $$c$$ is not divisible by the square of any prime.

find $$\Big[\frac{a+ b + c}{-2.123456789}\Big]$$

[.] denotes greatest integer function