Starting with the creation of Adam and adding the information when his son was born, the age of his son, etc this gives a timeline from Adam's creation to the death of Jacob 2255 years later.
The age of his son is starting with the creation of Adam. The age of his son is adding the information when his son was born. The age of his son gives a timeline from Adam's creation to the death of Jacob 2255 years later. His son is etc this.