The hexeicosillion is equal to \(10^{3\times 10^{78}+3}\) or \(10^{3\text{ quinvigintillion }3}\).[1] It is defined using Sbiis Saibian's generalization of Jonathan Bowers' -illion system.


Notation Lower bound Upper bound
Arrow notation \(1000\uparrow(1+10\uparrow78)\)
Down-arrow notation \(1000\downarrow\downarrow27\) \(6\downarrow\downarrow102\)
Steinhaus-Moser Notation 46[3][3] 47[3][3]
Copy notation 2[2[79]] 3[3[79]]
H* function H(H(25))
Taro's multivariable Ackermann function A(3,A(3,259)) A(3,A(3,260))
Pound-Star Notation #*((1))*(5,4,5,1,8)*5 #*((1))*(6,4,5,1,8)*5
BEAF {1000,1+{10,78}}
Hyper-E notation E(3+3E78)
Bashicu matrix system (0)(1)[16] (0)(1)[17]
Hyperfactorial array notation (56!)! (57!)!
Fast-growing hierarchy \(f_2(f_2(254))\) \(f_2(f_2(255))\)
Hardy hierarchy \(H_{\omega^22}(254)\) \(H_{\omega^22}(255)\)
Slow-growing hierarchy \(g_{\omega^{\omega^{\omega7+8}3+3}}(10)\)


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