How can I write this differential equation system in MATLAB?

I am newbie MATLAB user. How to write this equation system in MATLAB?

$$\frac{dN_{ik}}{dt}=\sum_{j=i}^{n}\sum_{l=1}^{n}\beta_{jl}b_{ikjl}S_{jl}N_{jl} - S_{ik}N_{ik}$$

Here, I want to know if I take $n=3$ or any constant number what kind of equation system will I have?

How can i run this loop without entering $\beta$, $b$ and $S$ functions. I just want to see matrix form of this system. Sorry for my bad English, thanks for help.