# Existence of a power series converging non-uniformly to a continuous function

I am wondering whether there exist a function $f(z) = \sum_{n\geq0} a_n z^n$ such that:

• $f$ converges and is continuous on the closed unit disk $D$ and
• the series $\sum_n a_n z^n$ does not converge uniformly on $D$.

I have tried to construct a counter-example, but with no success so far.

• Related: math.stackexchange.com/q/353760/462 (In the answer to the linked question, an $f$ is given that converges pointwise on the boundary of $D$, but its restriction to the boundary is discontinuous (so the convergence cannot be uniform). Commented May 13, 2013 at 14:06

It is shown there that for every closed subset $F$ of the boundary $\partial D$, there is such a series that converges everywhere on the closed disk to a continuous function, and whose set of non-uniform convergence is $F$. This means that the series converges uniformly in a neighborhood (open arc) of each point in $\partial D\setminus F$, but not in any neighborhood of any point in $F$.