PAMO 2021 Problem 1

Let $n$ be an integer greater than $3$ . A square of side length $n$ is divided by lines parallel to each side into $n^2$ squares of length $1$ . Find the number of convex trapezoids which have vertices among the vertices of the $n^2$ squares of side length $1$ , have side lengths less than or equal $3$ and have area equal to $2$ Note: Parallelograms are trapezoids.