  We investigate the dynamics of DNA translocation through a nanopore driven by
an external force using Langevin dynamics simulations in two dimensions (2D) to
study how the translocation dynamics depend on the details of the DNA
sequences. We consider a coarse-grained model of DNA built from two bases $A$
and $C$, having different base-pore interactions, {\textit e.g.}, a strong
(weak) attractive force between the pore and the base $A$ ($C$) inside the
pore. From a series of studies on hetero-DNAs with repeat units $A_mC_n$, we
find that the translocation time decreases exponentially as a function of the
volume fraction $f_C$ of the base $C$. %($\epsilon_{pC} < \epsilon_{pA}$). For
longer $A$ sequences with $f_C \le 0.5$, the translocation time strongly
depends on the orientation of DNA, namely which base enters the pore first. Our
studies clearly demonstrate that for a DNA of certain length $N$ with repeat
units $A_mC_n$, the pattern exhibited by the waiting times of the individual
bases and their periodicity can unambiguously determine the values of $m$, $n$
and $N$ respectively. Therefore, a prospective experimental realization of this
phenomenon may lead to fast and efficient sequence detection technic.
