Terrible tethrennon

The terrible tethrennon is equal to E100(#^^#^(9))^^#100 in Extended Cascading-E Notation. The term was coined by Sbiis Saibian.
== Approximations in other notations ==
Notation 	Approximation
Bird's array notation 	\(\{100,100 [1 \backslash 2 [2 \neg 2] 2] 2\}\)
Fast-growing hierarchy	\(f_{\varepsilon_{\varphi(9,0)+1}}(99)\)
Hardy hierarchy 	\(H_{\varepsilon_{\varphi(9,0)+1}}(100)\)
==Sources==
Category:Numbers
Category:Numbers by Sbiis Saibian
Category:Extended Cascading-E numbers
Category:Binary phi level