Tethrathoth-ad-tethrathoth-ad-gridgahlahiumium is equal to E100(#^^#)^(#^^#)^#^##100 using Extended Cascading-E Notation.[1] The term was coined by Sbiis Saibian.

Approximations in other notations

Notation Approximation
BEAF \(\{100,100 ((X \uparrow\uparrow X)^{X^X}) 2\}\)[2]
Bird's array notation \(\{100,101 [1 [1,2 \backslash 2] 2 \backslash 2] 2\}\)
Fast-growing hierarchy \(f_{\varepsilon_0^{\varepsilon_0^{\omega^{\omega^2}}}}(100)\)
Hardy hierarchy \(H_{\varepsilon_0^{\varepsilon_0^{\varepsilon_0^{\omega^{\omega^2}}}}}(100)\)
Slow-growing hierarchy ????


  1. Saibian, Sbiis. 4.3.7 Extended Cascading-E Numbers Part IOne to Infinity. Retrieved 2017-02-16.
  2. Using particular notation \(\{a,b (A) 2\} = A\ \&\ a\) with prime b.
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