Answer Happy

Using C programming define this program
recursively:
The series of pentagonal numbers can be defined recursively as
follows:
Complete the definition of
the pentagonal_numbers() function which takes a single
integer parameter n and returns the nth pentagonal number
(an integer). You can assume that n will be 1 or
more.
The pentagonal_numbers() function must be defined
recursively. Some examples of the function being
called are shown below.
Function to be completed:
int pentagonal_numbers(int n){
//insert code here
}