function r = ackerman(m, n)
  if ( m == 0 )
    r = n + 1;
  elseif ( n == 0 )
    r = ackerman(m-1, 1);
  else
    r = ackerman(m-1, ackerman(m, n-1));
  endif
endfunction

for i = 0:3
  disp(ackerman(i, 4));
endfor