RecursionJava

This a simple recursion test class to show understanding of it, the class contains 4 methods , a main to call all the other methods, a traingular recursion method to print out the nth number of a triangular base case (i.e 1,3,6,10,......), a greatest common denominator method to calculate the GCD of two particular numbers, and a Birthday recursive method which is to find the possiblity of people having the same birthday in a class or group of people.