The important levels are 61.8% (an-1 / an), 38.2% (an-2 / an), and 23.6% (an-3 / an). There are other important levels like 78.6% and 50%, which are not Fibonacci ratios but are nonetheless important. The 78.6% level is given by the square root of 61.8%, while the 50% level is a common convention.