User blog comment:Nayuta Ito/"I think this is the fastest" function (Part 1+1/2)/@comment-2033667-20150329232050/@comment-25337554-20150401035548

>actually Ackermann's function isn't variadic, because it has constant number of arguments (actually 2)

I used "Ackermann" for  Taro's multivariable Ackermann function, which is variadic.