Number of Antisymmetric Relations on a set of N elements

Given a positive integer N, the task is to find the number of Antisymmetric Relations on the given set of N elements. Since the number of relations can be very large, so print it modulo 109+7.
A relation R on a set A is called Antisymmetric if and only if (a, b) € R and (b, a) € R, then a = b is called antisymmetric, i.e., the relation R = {(a, b)→ R | a ≤ b} is anti-symmetric, since a ≤ b and b ≤ a implies a = b.