Adding the indices of n elements of a nxn table to get all possible combinations that equal n(n+1)/2

Question

I have a 4x4 table with the indices (i,j). I\'m working with MATLAB, so the indices start with 1.

(1,1),(1,2),(1,3),(1,4),

(2,1),(2,2),(2,3),(2,4),

(3,1