I read about Graham number and TREE(3).
Graham number is: $f^{64}(4)$ where $f(n)=3\uparrow^n 3$
My question is: If there is a way to write TREE(3) via $f^a(b)$?
(and of course $f(n)$ can be different, but at the form of: $ x\uparrow^yz $)
Thank you!
No, $TREE(3)$ is in a completely different league. Graham's number has level $f_{\omega+1}$ in the fast-growing hierarchy, $TREE(3)$ is far beyond level $f_{\Gamma_0}$
So, the index $a$ in the function you want to arrive at $TREE(3)$ would be indistinguishable of $TREE(3)$ itself.