  We consider the number of spanning trees in circulant graphs of $\beta n$
vertices with generators depending linearly on $n$. The matrix tree theorem
gives a closed formula of $\beta n$ factors, while we derive a formula of
$\beta-1$ factors. Using the same trick, we also derive a formula for the
number of spanning trees in discrete tori. Moreover, the spanning tree entropy
of circulant graphs with fixed and non-fixed generators is compared.
