This is a function whose domain is a set of consecutive integers. they are finite and infinite.

The set of consecutive integers are:



If the function is finite, then there are two values  and , being , in which this function is valid, then:


being  the set of integers in the interval defined by 

If the function is infinite, the function is valid in the set of all integers then:


And -∞+∞ 

Graph a should be your answer