# Octation

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Octation refers to the 8th hyperoperation starting from addition. It is equal to $$a \uparrow\uparrow\uparrow\uparrow\uparrow\uparrow b$$ in Knuth's up-arrow notation[1][2]

Octation can be written in array notation as $$\{a,b,6\}$$, in chained arrow notation as $$a \rightarrow b \rightarrow 6$$ and in Hyper-E notation as E(a)1#1#1#1#1#b.

Octational growth rate is equivalent to $$f_7(n)$$ in the fast-growing hierarchy.