С 1 в знаменателе 0
с 2 - 1 (1/2)
с 3 - 2 (1/3, 2/3)
с 4 - 2=3-1 (1/4, 3/4) (1/2 = 2/4)
с 5 - 4 (1/5, 2/5, 3/5, 4/5)
с 6 - 2 = 5-3 (1/6, 5/6) (2/6 = 2/3, 3/6 = 1/2, 4/6 = 2/3)
с 7 - 6 (1/7,2/7,3/7,4/7,5/7,6/7)
с 8 - 4=7-3 (1/8, 3/8,5/8,7/8) (2/8 = 1/4, 4/8=1/2, 6/8 = 3/4)
с 9 - 6=8-2 (1/9, 2/9, 4/9, 5/9, 7/9, 8/9) (1/3 = 3/9 и 2/3 = 6/9)
1+2+2+4+2+6+4+6 = 19