A) 27+6+3 = 36 -> roll 4, 5, 10
B) 27+6+3 = 36 -> roll 11, 16, 17
C) 25+10+1 = 36 -> roll 3, 6, 9
D) 5+10+1 = 36 -> roll 12, 15, 18
E) 21+15 = 36 -> roll 7, 8
F) 21+15 = 36 -> roll 13, 14

sum | prob/216 | group
3 1 C
4 3 A
5 6 A
6 10 C
7 15 E
8 21 E
9 25 C
10 27 A
11 27 B
12 25 D
13 21 F
14 15 F
15 10 D
16 6 B
17 3 B
18 1 D