Pentacthulcross is equal to E100#^^^##100 in Extended Cascading-E Notation.[1] The term was coined by Sbiis Saibian.


The name of this number is based on the number pentacthulhum and the word "cross".

Approximations in other notations

Notation Approximation
BEAF \(\{X,X,2,2\}\ \&\ 100\)
Bird's array notation \(\{100,100[1[1 \neg 3]1 \backslash 2]2\}\)
Hyperfactorial array notation \(100![1(1)1,1,2,2]\)
Fast-growing hierarchy (with this system of fundamental sequences) \(f_{\varphi(1,1,0)}(99)\)
Hardy hierarchy \(H_{\varphi(1,1,0)}(100)\)
Slow-growing hierarchy \(g_{\vartheta(\Omega_2+\vartheta_1(\Omega_2+1))}(100)\)


  1. Saibian, Sbiis. 4.3.9 - Forging Extended Cascading-E Numbers Part III. Retrieved 2021-02-27.
Community content is available under CC-BY-SA unless otherwise noted.