I am taking a class on Automata and Formal Languages and I need to solve an exercise, but I have no idea where to start from. It sounds like this:
Decide the coefficients of the words in $\{a,b\}^*$, which in the following formal power series occur (the semirings are already known):
$(a+b)^{n}, (a+b)^*$ (for the boolean semiring and for the semiring of the nonnegative integers plus infinity)
Can you help me please? And could you indicate me some literature in which I could read something about formal power series?
Thank you in advance.
As to literature:
G. Lallement, Semigroups and combinatorial applications, John Wiley & Sons Inc (1979), Chapter 9.