Tetration

Rare card · No. 73220

In mathematics, tetration (or hyper-4) is an operation based on iterated, or repeated, exponentiation. There is no universal notation for tetration, though Knuth's up arrow notation a ↑↑ n {\displaystyle a\uparrow \uparrow n} and the left-exponent n a {\displaystyle {}^{n}a} are common. Under the definition as repeated exponentiation, n a {\displaystyle {^{n}a}} means a a ⋅ ⋅ a...

Read on Wikipedia · Image AJRobbins at English Wikipedia, Public domain