Thanks. Obviously http://en.wikipedia.org/wiki/Knuth%27s_up-arrow_notation http://en.wikipedia.org/wiki/Knuth%27s_up-arrow_notation Shorter read: http://www.da

Thanks. Obviously http://en.wikipedia.org/wiki/Knuth%27s_up-arrow_notation http://en.wikipedia.org/wiki/Knuth%27s_up-arrow_notation Shorter read: http://www.daviddarling.info/encyclopedia/K/Knuths_up-arrow_notation.html http://www.daviddarling.info/encyclopedia/K/Knuths_up-arrow_... , which comes quickly to next step: Three up-arrows together represent a still more vastly powerful operator, equivalent to hyper5 or pentation, or a power tower of power towers