Write a C function which calculates the following series: In = 2.5xn-1 - 1.2xn-2 +1.5 The function should return a float value for x_n and takes no argument (ie: the argument is of type void). The function should assume that x0 = 0 and x1 = 0. On the first call to the function x2 is returned. On the second call x3 is returned, etc. The function prototype is: 1: float series (void);