Circles Chain TIKZ

\begin{tikzpicture}
\node at (0,.5) {$A$};
\node at (1,.5) {$B$};
\filldraw (0,0) circle (3pt);
\draw (1,0) circle (3pt);
\filldraw (2,0) circle (3pt);
\draw (3,0) circle (3pt);
\filldraw (4,0) circle (3pt);
\draw (5,0) circle (3pt);
\filldraw (6,0) circle (3pt);
\draw (7,0) circle (3pt);
\end{tikzpicture}