Code for generating key using logistic equation for k no of times?

I want code for key genetation using logistic equation: value of n= 1 to 256 X(n+1)= r*X(n)*(1-X(n)); (% logistic eq) value of i from 1 to 256 kt(i)= x(n+1); k(i)=floor(mod(10^14, kt(i), 256));