The octeicosillion is equal to \(10^{3\times 10^{84}+3}\) or \(10^{3\text{ septenvigintillion }3}\).[1] It is defined using Sbiis Saibian's generalization of Jonathan Bowers' -illion system.


Notation Lower bound Upper bound
Arrow notation \(1000\uparrow(1+10\uparrow84)\)
Down-arrow notation \(1000\downarrow\downarrow29\) \(789\downarrow\downarrow30\)
Steinhaus-Moser Notation 48[3][3] 49[3][3]
Copy notation 2[2[85]] 3[3[85]]
H* function H(H(27))
Taro's multivariable Ackermann function A(3,A(3,279)) A(3,A(3,280))
Pound-Star Notation #*((1))*(8,0,1,3,3)*6 #*((1))*(0,5,2,6)*8
BEAF {1000,1+{10,84}}
Hyper-E notation E(3+3E84)
Bashicu matrix system (0)(1)[16] (0)(1)[17]
Hyperfactorial array notation (60!)! (61!)!
Fast-growing hierarchy \(f_2(f_2(274))\) \(f_2(f_2(275))\)
Hardy hierarchy \(H_{\omega^22}(274)\) \(H_{\omega^22}(275)\)
Slow-growing hierarchy \(g_{\omega^{\omega^{\omega8+4}3+3}}(10)\)


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