A ⊆ C {\displaystyle A\subseteq \mathbb {C} }
f ( z ) = ∑ n = − ∞ + ∞ c n ( z − z 0 ) n {\displaystyle f(z)=\sum _{n=-\infty }^{+\infty }c_{n}(z-z_{0})^{n}}
c n ≠ 0 {\displaystyle c_{n}\neq 0}
g ( z ) = ∑ n = 0 + ∞ a n ( z − z 0 ) n {\displaystyle g(z)=\sum _{n=0}^{+\infty }a_{n}(z-z_{0})^{n}}
a 0 ≠ 0 {\displaystyle a_{0}\neq 0}
f ( z ) = a 0 ( z − z 0 ) n + a 1 ( z − z 0 ) n − 1 + ⋯ + a n + 1 ( z − z 0 ) + ⋯ {\displaystyle f(z)={\frac {a_{0}}{(z-z_{0})^{n}}}+{\frac {a_{1}}{(z-z_{0})^{n-1}}}+\cdots +a_{n+1}(z-z_{0})+\cdots }
