Geegol

The geegol is equal to {10,100,4} in BEAF, also written as 10{4}100 in the bracket-operator notation. In arrow notation, this number is written as \(10 \uparrow\uparrow\uparrow\uparrow 100\). The term was coined by Jonathan Bowers.

This number is also called hecta-petaksys by Sbiis Saibian, and it's equal to E1#1#1#100 in Hyper-E notation.

In the fast-growing hierarchy geegol can be approximated as \(f_5(100)\).