Solve Lumping Differential equation

Hi guys, I'm having a rough time solving this equation :

dF(i)/dt = -K(i).F(i) + Sum(from j= i+2 to N) of K(j).P(i,j).F(j)

I have the matrix K and the P as well. any suggestings on how solve this equation within matlab? Thank you

[hosein Javan]

is the independent variable "t"? does the summation include the independent variable or is it constant? if so it is a linear first order differential equation. please in order to clarify, attach the image of your equation.

[amairi taheni]

yes, t is independent, only F depends of t. K depends of i (or j) and P depends on i and j.