Population Decay in R

Hi,

I am new to R.  I am trying to plot the decay of a population over time
(0-50yrs).  I have the initial population value (5000) and the mortality
rate (0.26/yr) and I can't figure out how to apply this so I get a
remaining population value each year.  In excel (ignoring headings) I
would put 5000 in A1, in B2 I would enter the formula A1*0.26, and then in
A2 (the next years population) I would subtract B2 from A1.  I would
continue this process untill I had calculated the population for the 50th
year.  Any ideas of how to do this in R?  :-/