Some functions and the exercise -- 例1詳解. \(a_n=3+4n\) 改為 \(a_n=3+4^n\)
Generating functions

Unsort

\( \displaystyle\frac{1}{(1-ax)^n}=\displaystyle\sum_{r=0}^{\infty} \begin{pmatrix} n+r-1 \\ r \end{pmatrix} (ax)^r \)

多項式定理

Generating function

Convolution

Convolution

Combination problem

generating function to solve combination problem -- continue -- exercise 1 -- exercise 2

Partitions of integers

partitions of integers -- exercise

Exponential generating function