Heads-Tet-2-primol is a number equal to R**(4) using Primarial Functions. It is equal to 7↑↑5↑↑3↑↑2 (=7↑↑5↑↑27 or 7↑↑R**(3)). The term was coined by Licorneuhh.[1]


Notation Lower bound Upper bound
Arrow notation \(7 \uparrow\uparrow 5 \uparrow\uparrow 27\)
Hyper-E notation E[7]1#(E[5]1#27)
Hyper-E notation (base 10) E1#(E3.494#26) E1#(E3.495#26)
BEAF {7,{5,27,2},2}
Hyperfactorial array notation (28!1)!1 (29!1)!1
Fast-growing hierarchy \(f_3(f_3(25))\) \(f_3(f_3(26))\)
Hardy hierarchy \(H_{\omega^3}(H_{\omega^3}(26))\) \(H_{\omega^3}(H_{\omega^3}(27))\)
Slow-growing hierarchy \(g_{\varepsilon_0}(g_{\varepsilon_0}(26))\) \(g_{\varepsilon_0}(g_{\varepsilon_0}(27))\)


  1. Numbers | Licorneuhh's numbers site (retrieved at UTC 15:35 14/01/2021)
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