  Let $f(m,n)$ be the number of primitive lattice triangulations of $m\times n$
rectangle. We compute the limits $\lim_n f(m,n)^{1/n}$ for $m=2$ and $3$. For
$m=2$ we obtain the exact value of the limit which is equal to
$(611+\sqrt{73})/36$. For $m=3$, we express the limit in terms of certain
Fredholm's integral equation on generating functions. This provides a
polynomial time algorithm for computation of the limit with any given precision
(polynomial with respect the the number of computed digits).
