We have,
R = {(1, 1), (2, 2), (3, 3), (1, 3)}
As, (a, a) R, for all values of a A
So, R is a reflexive relation
R can be a symmetric and transitive relation only when element (3, 1) is added
Hence, the ordered pairs to be added to R to make the smallest equivalence relation is (3, 1).