  In this note, we give a closed formula for the partition function of the
dimer model living on a (2 x n) strip of squares or hexagons on the torus for
arbitrary even n. The result is derived in two ways, by using a Potts model
like description for the dimers, and via a recursion relation that was obtained
from a map to a 1D monomer-dimer system. The problem of finding the number of
perfect matchings can also be translated to the problem of finding a minmal
feedback arc set on the dual graph.
