[oak perl] GNU and recursion

[George Woolley]

My understanding from the GNU project site is that:
      GNU is a recursive acronym for "GNU's Not Unix'" 

So I'm thinking: 
GNU(0)   equals   GNU
GNU(1)   equals   GNU's Not Unix

My first question: what do
GNU(2), GNU(3), etc. equal?

And my second question:
what would the Perl function look like 
for generating the values of GNU(0), GNU(1), GNU(2), etc.?