eqs

$\displaystyle x_{n+1}=ax_n+b \quad {\rm mod}\,\mu$ (1)

$\displaystyle {\partial n\over \partial t}=D\left({\partial^2n\over \partial x^2} + {\partial^2n\over \partial y^2}\right)$ (2)

$\displaystyle D={\Delta x^2\over 4\Delta t}={1\over 4}$ (3)

$\displaystyle {n\over t}=D{n\over L^2}$ (4)

$\displaystyle L=\sqrt{tD}$ (5)

$\displaystyle n(r,t)={1\over 4\pi Dt}\exp(-r^2/4Dt)$ (6)

$\displaystyle \bar{r^n}$

$\textstyle =$

$\displaystyle \int_0^\infty 2\pi r^{n+1} n(r,t) dr$

(7)