fun ackermann = int by int m, int n
  return when(m == 0,
    n + 1,
	when(n == 0,
	ackermann(m - 1, 1),
	ackermann(m - 1, ackermann(m, n - 1))))
end
for int m = 0; m <= 3; ++m
  for int n = 0; n <= 6; ++n
    writeLine("Ackermann(" + m + ", " + n + ") = " + ackermann(m, n))
  end
end