# BASIC256 since 0.9.9.1 supports functions
for m = 0 to 3
   for n = 0 to 4
      print m + " " + n + " " + ackermann(m,n)
   next n
next m
end

function ackermann(m,n)
   if m = 0 then
      ackermann = n+1
   else
      if n = 0 then
         ackermann = ackermann(m-1,1)
      else
         ackermann = ackermann(m-1,ackermann(m,n-1))
      endif
   end if
end function