Tethracross-by-deuteron is equal to E100#^^##100#^^##100 using Extended Cascading-E Notation.[1] The term was coined by Sbiis Saibian. This number belongs to the Tethracross regiment.

Approximations in other notations

Notation Approximation
BEAF \(\{100,100 (X \uparrow\uparrow\uparrow X) 3\}\)[2]
Fast-growing hierarchy \(f_{\zeta_0 2}(100)\)
Hardy hierarchy \(H_{\zeta_0^2}(101)\)
Slow-growing hierarchy \(g_{\vartheta(\zeta_{\Omega2}+\zeta_{\Omega+1})}(100)\)


  1. Saibian, Sbiis. 4.3.7 Extended Cascading-E Numbers Part IOne to Infinity. Retrieved 2017-01-02.
  2. Using particular notation \(\{a,b (X \uparrow\uparrow X) c \#\}\) for \(\{X \uparrow\uparrow b\ \&\ a (X \uparrow\uparrow X) c-1 \#\}\)
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