Write a c program

Elmo has just bagged his first job as a delivery boy for Amazon and his first day of work involves delivering parcels to Sesame Street. Sesame street has houses arranged sequentially, i.e. one after the other. Elmo gets to know from his supervisor that on a given day no two adjacent houses ever get a parcel. Moreover, at least one out of every three adjacent houses gets a parcel on any given day. Elmo’s mind boggles up just thinking about all the delivery patterns possible on any given day. Being a Sesame Street friend, help Elmo figure out the math and find the number of delivery patterns possible. Input: Integer n(number of houses) (1<=n<=60) Output: Number of possible delivery Patterns Example: Input :- 3 Output :- 4