Graycode (Algorithm 246 [Z]) CACM December, 1964 Boothroyd, J. CA641202 JB March 9, 1978 3:44 PM 969 5 969 969 5 969 969 5 969 2834 5 969 969 6 969 2045 6 969 2417 6 969 2466 6 969