The meicosillion is equal to \(10^{3\left(10^{63}\right)+3}\) or \(10^{3\text{ vigintillion }3}\).[1] The term was coined by Aarex Tiaokhiao.


Notation Lower bound Upper bound
Arrow notation \(1000\uparrow(1+10\uparrow63)\)
Down-arrow notation \(1000\downarrow\downarrow22\) \(551\downarrow\downarrow24\)
Steinhaus-Moser Notation 38[3][3] 39[3][3]
Copy notation 2[2[64]] 3[3[64]]
H* function H(H(20))
Taro's multivariable Ackermann function A(3,A(3,209)) A(3,A(3,210))
Pound-Star Notation #*((1))*(11,6)*14 #*((1))*(6,2,1,1,1)*5
BEAF {1000,1+{10,63}}
Hyper-E notation E(3+3E63)
Bashicu matrix system (0)(1)[14] (0)(1)[15]
Hyperfactorial array notation (48!)! (49!)!
Fast-growing hierarchy \(f_2(f_2(204))\) \(f_2(f_2(205))\)
Hardy hierarchy \(H_{\omega^22}(204)\) \(H_{\omega^22}(205)\)
Slow-growing hierarchy \(g_{\omega^{\omega^{\omega6+3}3+3}}(10)\)


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