Assume there is a sequence of integers, [a, a2, a3, the pattern of this sequence is that an an-1 + (n-1) and a1-1. Here are the first five elements in the sequence: = 1, a2-1 + 1=2, a3 = 2 + 2 = 4,a4 _ 4 + 3 = 7, as _ 7 + 4 = 1 user to input an integer (larger than 1) to be the position index for this sequence and calculate the value of that position in the sequence. Use recursion function (a function calling itself) to achieve this purpose. Name your file Hw3 q2_code.c. 1 ...). Please write a program to ask the (TIP: below is an example of recursion function)