-Up Arrow Notation https://en.wikipedia.org/wiki/Knuth%27s_up-arrow_notation -Chained Arrow Notation https://en.wikipedia.org/wiki/Conway_chained_arrow_notation -TREE Function https://en.wikipedia.org/wiki/Kruskal%27s_tree_theorem -Extended Tree Function https://scratch.mit.edu/projects/172541425/ -M Notation https://scratch.mit.edu/projects/319667892/
