[1,1,2,3,4,3,5,4,5,6,5,7,5,8,7,6,7,8,9,7,9,8,11,7,10,7,11,8,13,9,10,9,11,9,13,10,11,10,13,11,12,11,13,12,13,14,9,14,11,14,13,15,11,15,13,16,11,16,13,17,11,17,12,17,13,18,13,19,12,19,13,20]