Generating function
A generating function is a formal power series where the coefficient at $x^n$ usually counts the number of combinatorial objects of size $n$.
Sometimes the coefficients are normalized, as is the case with exponential generating functions, where the $n$th coefficient is divided by $n!$. This can give the operations on the series a different meaning.
Problems
- Bus Routes
- The Child and Binary Tree
- Devu and Locks
- Devu and Birthday Celebration
- Tricolored Coin Fountains