What are some of the implementation of recursive functions?

Answer 1

Most popular example:
https://www.sololearn.com/learn/662/?ref=app

Answer 2

here is 2 examples of recursion

https://code.sololearn.com/cTcbz3rrJaw7/?ref=app

https://code.sololearn.com/c4qyGd6oeAsQ/?ref=app

Answer 3

What language are you interested in? write a more specific question! so that people can understand you :)