User blog:Nayuta Ito/tetrational logarithm

For tetrational calculation, how about using this operator (and the tables)?

When $$lim_{n \to \infty}x\uparrow \uparrow n=(y\uparrow)^n a$$,

$$\downarrow og _x y=a$$

(note: The mathematical definition requires n to infinity, but you only have to calculate up to n=3 to approximate.)