The function f (x) defined in positive integer set has f (M + n) = f (m) + F (n) + 4 (M + n) -· 2 for any m, N, and f (1) = 1 If m ^ 2-tm-1

The function f (x) defined in positive integer set has f (M + n) = f (m) + F (n) + 4 (M + n) -· 2 for any m, N, and f (1) = 1 If m ^ 2-tm-1

Let m = x, n = 1, f (x + 1) = f (x) + 4x + 3; so: F (2) = f (1) + 4 * 1 + 3f (3) = f (2) + 4 * 2 + 3f (4) = f (3) + 4 * 3 + 3. F (x) = f (x-1) + 4 * (x-1) + 3, f (x) = f (1) + 4 * (1 + 2 + 3 +... + (x-1)) + 3 * (x-1) = 2x & sup2; + X-2. Obviously, the minimum value of F (x) is 1, so M & sup2; - TM-1