OABCD is a pentagon in which \(OA\) and \(CB\) are parallel and \(OD\) and \(AB\) are parallel. If
\[
\overrightarrow{OA}=\overrightarrow{a},
\qquad
\overrightarrow{OD}=\overrightarrow{d},
\]
and
\[
\frac{OA}{CB}=2,
\qquad
\frac{OD}{AB}=\frac13,
\]
then
\[
\overrightarrow{AD}+\overrightarrow{OC}+\overrightarrow{DC}
\]
is equal to: