section_path: Specifying a function/By recurrence
section_name: By recurrence
paragraph_text: By recurrence
  
  Functions whose domain are the nonnegative integers, known as sequences, are sometimes defined by recurrence relations.
  
  The factorial function on the nonnegative integers (n ↦ n ! {\displaystyle n\mapsto n!}) is a basic example, as it can be defined by the recurrence relation
  
  and the initial condition