Design a class to overload a function series() as follows: 
(i) double series(double n) with one double argument and returns the sum of the series.
sum = 1/1 + 1/2 + 1/3 + ….. 1/n
(ii) double series(double a, double n) with two double arguments and returns the sum of the series.
sum = 1/a² + 4/a⁵ + 7/a⁸ + 10/a¹¹ ….. to n terms