David Joyner wrote to GAP Forum:
> One example I've been trying to illustrate in my undergraduate
> algebra class is the following:
> (a) the coefficients of X^i in the power series expansion
> of 1/(1 + X^3 + X^4) (mod 2), [...]
> GAP does all these, but (a) is the hardest. [...] It is
> so slow that it is almost impractical for classroom use [...]
This series may be quickly computed using the Newton iteration
for inversion of a power series. Here it nicely specializes to
f (X) = 1 0 f (X) = f (X^2) (1 + X^3 + X^4) mod X^2^(n+1) n+1 n
which may be quickly computed via additions and shifts.
What is the source of this problem?