[GAP Forum] Formal power series over GF(2)

[Yannis Michos]

 Dear Forum

 Suppose 
that I have a univariate $F(t) = {\sum}_{n \geq 0} a_{n} t^{n}$ or a 
bivariate $G(s,t) = {\sum}_{n,k \geq 0} a_{n,k} s^{n}t^{k}$ 

generating 
function on one variable t or two variables s, t respectively, 
with all coeffiecients $a_{n}$ or $a_{n,k}$ on the field GF(2) of two 
numbers or, 

which is actually my case, on the ring GF(2)[X_{1}, X_{2}, 
..., X_{m}] on $m$ commuting intederminates. 

Is there a Gap enviroment 
and immediate command or algorithm to compute $a_{n}$ or $a_{n,k}$, 
i.e., [t^{n}]F(t) or [s^{n}t^{k}]G(s,t), if we know F or G?
  
 Example: The generating function of Pascal's triangle, taken modulo 2, 
is G(s, t) = 1/[1 + (1+t)s]. Suppose I want the binomial coefficient 
C(3,8) mod 2, 

i.e., the term [s^{3}t^{8}]G(s,t). Can I get it 
immediately using a Gap command?