# I'm 16!

**Calculus**Level 4

A function \(F(x,y,z)\) is known to have \(F(1,1,1) = 1, F(2,1,1) = 4, F(2,2,1) = 8, F(2,2,2) = 173\). Find the sum of all the values of \(c\) satisfying

\[\displaystyle \left \lfloor {\nabla}_{5\textbf{i} + 9\textbf{j} + c\textbf{k}} F \right \rfloor = 16\]

**Note**

Directional Derivative is found approximately.