  The anisotropic superconductivity and the density wave have been investigated
by applying the Kadanoff-Wilson renormalization group technique to the
quasi-one-dimensional system with finite-range interactions. It is found that a
temperature (T) dependence of response functions is proportional to exp(1/T) in
a wide region of temperature even within the one-loop approximation. Transition
temperatures are calculated to obtain the phase diagram of the
quasi-one-dimensional system, which is compared with that of the
pure-one-dimensional system. Next-nearest neighbor interactions (V_2) induce
large charge fluctuations, which suppress the d_{x^2 -y^2}-wave singlet
superconducting (dSS) state and enhance the f-wave triplet superconducting
(fTS) state. From this effect, the transition temperature of fTS becomes
comparable to that of dSS for large V_2, so that field-induced f-wave triplet
pairing could be possible. These features are discussed to comprehend the
experiments on the (TMTSF)_2PF_6 salt.
