11,348
pages

The tetrofaxul is equal to 200!2 in Hyperfactorial array notation.[1][2] Tetrofaxul can be thought as "tetrofactorial" of 200, which is, by analogy with expofactorial, means $$f(n) = n \uparrow\uparrow (n-1) \uparrow\uparrow (n-2) \cdots 4 \uparrow\uparrow 3 \uparrow\uparrow 2 \uparrow\uparrow 1$$. Thus, tetrofaxul can be represented as $$200 \uparrow\uparrow 199 \uparrow\uparrow 198 \cdots 4 \uparrow\uparrow 3 \uparrow\uparrow 2 \uparrow\uparrow 1$$. This is based on tetration. The term was coined by Lawrence Hollom.

## Contents

### Etymology

The name of this number is based on Greek prefix "tetra-" and the number "faxul".

### Approximations in other notations

Notation Approximation
Hyper-E notation $$E10\#10\#197$$
Up-arrow notation $$10 \uparrow\uparrow\uparrow 198$$
Chained arrow notation $$10 \rightarrow 198\rightarrow 3$$
BEAF $$\{10,198,3\}$$
Fast-growing hierarchy $$f_4(200)$$
Hardy hierarchy $$H_{\omega^4}(200)$$
Slow-growing hierarchy $$g_{\zeta_0}(200)$$