  The quarter-filling extended Hubbard model on the triangular lattice is
studied to explore pairing instability in the three-fold charge-ordered (CO)
metal. We derive a second-order strong-coupling effective Hamiltonian of doped
carriers into the three-fold CO insulator at electron density of $n=2/3$, and
then study the $f$- and $d_{xy}$-wave superconductivities down to $n=1/2$ by
using the BCS mean-field approximation. It is found that the triplet $f$-wave
pairing is more stable than the $d_{xy}$-wave one. We also point out that this
coexisting state of the charge ordering and superconductivity is possible to
have critical temperature $T_c \sim 0.01 t$.
