\begin{tikzpicture}
\begin{axis}[
axis lines*=middle,
enlargelimits = true,
ymin=-1,
ymax=1,
xmin=-1,
xmax=20,
axis line style={->,>=stealth},
xlabel={\Large $n$},
ylabel={\Large $y[n]$},
yticklabel style = {yshift=0.2cm},
xticklabel style = {yshift=-0.1cm},
every axis x label/.style={
	at={(ticklabel* cs:1)},
	anchor=north,
},
every axis y label/.style={
	at={(ticklabel* cs:1)},
	anchor=south,
},
ytick={-1, 1},
xtick=\empty,
every outer y axis line/.append style={white!15!black},
every y tick label/.append style={font=\color{white!15!black}},
legend style={draw=white!15!black,fill=white,legend cell align=left}]
\addplot [ycomb, mark=*, fill=white, mark options={scale=1.5, fill=white}, line width=1.5pt, forget plot, domain=0:20, samples=21] {0};

\end{axis}
\end{tikzpicture}