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Googology Wiki

The ogdontolus is equal to E100#80100 in Extended Hyper-E Notation.[1] It is also equal to E100#^#80 in Cascading-E notation. The term was coined by Sbiis Saibian.

Approximations in other notations

Notation Approximation
BEAF \(\{100,81 (1) 2\}\)
Bird's array notation \(\{100,81 [2] 2\}\)
Hyperfactorial array notation \(100![[1,100],98,78]\)
X-Sequence Hyper-Exponential Notation \(100\{X^X\}79\)
Fast-growing hierarchy \(f_{\omega^{79}}(100)\)
Hardy hierarchy \(H_{\omega^{\omega^{79}}}(100)\)
Slow-growing hierarchy \(g_{\theta(\Omega^{78} \omega)}(100)\)


  1. Saibian, Sbiis. Extended Hyper-E Numbers. Retrieved 2017-01-30.