If $g(z)=(z-a)^nf(z)$ with $f\in H(D(a,r)\setminus \{a\})$.
Can we said that $g^{(k)}(a)=0$ for all $k\in \{0,1,...,n-1\}$?
$f(z)=\frac1{(z-a)^3}\in H(D(a,r)\setminus\{a\})$, yet the first derivative of $(z-a)^4f(z)$ is $1$ at $z=a$.
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$f(z)=\frac1{(z-a)^3}\in H(D(a,r)\setminus\{a\})$, yet the first derivative of $(z-a)^4f(z)$ is $1$ at $z=a$.