The ogdacthulhum (also called heptacthularxihect) is equal to E100#^^^^^^#100 = E100#{6}#100 in Extended Cascading-E Notation.[1] The term was coined by Sbiis Saibian.


The name of this number is based on the words "octation" and "Cthulhu".

Approximations in other notations

Notation Approximation
BEAF \(\{X,X,1,5\}\ \&\ 100\)
Bird's array notation \(\{100,100 [1 [1\neg3] 1 [1\neg3] 1 [1\neg3] 1 [1\neg3] 2] 2\}\)
Hyperfactorial array notation \(100![1(1)1(1)1(1)1(1)2]\)
Fast-growing hierarchy \(f_{\varphi(4,0,0)}(99)\)
Hardy hierarchy \(H_{\varphi(4,0,0)}(100)\)
Slow-growing hierarchy \(g_{\vartheta(\Omega_{2}4)}(100)\)


  1. Saibian, Sbiis. 4.3.11 - Forging Extended Cascading-E Numbers Part V. Retrieved June 2014.
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