Undecation is the 11th hyperoperation, which is equal to the binary function \(\uparrow^{9}\) in Knuth's up-arrow notation.[1]

The n undecated to m is n decated to n decated to ... decated to n (m n's).

"a undecated to b" can be written in BEAF as \(\{a,b,9\}\), in chained arrow notation as \(a \rightarrow b \rightarrow 9\) and in Hyper-E notation as E[a]1#1#1#1#1#1#1#1#b.

Undecational growth rate is comparable to \(f_{10}(n)\) in the fast-growing hierarchy.

Cloudy176 called it Hendecation in his faketest F page.[2]


n undecated to 2 = \(a \uparrow^{9} 2\) = \(a \uparrow^{8} a\)


See also

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