Packeges challenge by Udemy Video - Tim Buchalka
https://www.udemy.com/course/java-the-complete-java-developer-course/
// Create a suitably named package containing a class called Series
// with the following static methods:
// nSum(int n) returns the sum of all numbers from 0 to n. The first 10 numbers are:
// 0, 1, 3, 6, 10, 15, 21, 28, 36, 45, 55.
//
// factorial(int n) returns the product of all numbers from 1 to n
// i.e. 1 * 2 * 3 * 4 ... * (n - 1) * n.
// The first 10 factorials are:
// 0, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880, 3628800.
//
// fibonacci(n) returns the nth Fibonacci number. These are defined as:
// f(0) = 0
// f(1) = 1
// f(n) = f(n-1) + f(n-2)
// (so f(2) is also 1. The first 10 fibonacci numbers are:
// 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55.
//
// When you have tested your functions, delete the Main class and
// produce a jar file.
//
// Create a new project and add your Series library, then test the
// three methods in the main() method of your new project.