The penhexo is equal to s(5,5,6) in strong array notation. The term was coined by wiki user Hyp cos. It can be represented in up-arrow notation as \(5\uparrow\uparrow\uparrow\uparrow\uparrow\uparrow5\) (5 octated to 5). This number is also equal to s(5,2,7) and s(5,6,1,2).