既然已经明确指出 f(x) 是二次函数,那么可以设f(x) = ax^2 + bx + c利用 f(0) = 1则 c =1f(x) = ax^2 + bx + 1f(x+1) = a(x+1)^2 + b(x+1) + 1 = ax^2 + (b+2a)x + a + b + 1f(x+1) - f(x) = {ax^2 + (b+2a)x + a + ...