We have studied Lagrange's four-square theorem and is denoted by g (2) = 4. i.e., any number can be expressible in sum of squares of four positive integers. Now my question is, here g (2) = 4, where 4 must be reduced to 3 except for numbers of the form $4^n$ (8k + 7). Can you generalize the difficulties, if the number in the form $4^n$ (8k + 7) will trouble to reduce in g (2) = 4 to 3? Also, I am looking the proof or idea to prove g (7) = 143, g (8) = 279, g (9) = 548 and g (10) = 1079.